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draconisplusplus/subprojects/quill-4.2.0/README.md
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2024-06-02 06:03:21 -04:00

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<div align="center">
<a href="https://github.com/odygrd/quill">
<img width="125" src="https://i.postimg.cc/DZrH8HkX/quill-circle-photos-v2-x2-colored-toned.png" alt="Quill logo">
</a>
<h1>Quill</h1>
<div>
<a href="https://github.com/odygrd/quill/actions?query=workflow%3Alinux">
<img src="https://img.shields.io/github/actions/workflow/status/odygrd/quill/linux.yml?branch=master&label=linux&logo=linux&style=flat-square" alt="linux-ci" />
</a>
<a href="https://github.com/odygrd/quill/actions?query=workflow%3Amacos">
<img src="https://img.shields.io/github/actions/workflow/status/odygrd/quill/macos.yml?branch=master&label=macos&logo=apple&logoColor=white&style=flat-square" alt="macos-ci" />
</a>
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<img src="https://img.shields.io/github/actions/workflow/status/odygrd/quill/windows.yml?branch=master&label=windows&logo=windows&logoColor=blue&style=flat-square" alt="windows-ci" />
</a>
</div>
<div>
<a href="https://codecov.io/gh/odygrd/quill">
<img src="https://img.shields.io/codecov/c/gh/odygrd/quill/master.svg?logo=codecov&style=flat-square" alt="Codecov" />
</a>
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<img src="https://img.shields.io/codacy/grade/cd387bc34658475d98bff84db3ad5287?logo=codacy&style=flat-square" alt="Codacy" />
</a>
<a href="https://www.codefactor.io/repository/github/odygrd/quill">
<img src="https://img.shields.io/codefactor/grade/github/odygrd/quill?logo=codefactor&style=flat-square" alt="CodeFactor" />
</a>
</div>
<div>
<a href="https://opensource.org/licenses/MIT">
<img src="https://img.shields.io/badge/license-MIT-blue.svg?style=flat-square" alt="license" />
</a>
<a href="https://en.wikipedia.org/wiki/C%2B%2B17">
<img src="https://img.shields.io/badge/language-C%2B%2B17-red.svg?style=flat-square" alt="language" />
</a>
</div>
<p><b>Asynchronous Low Latency C++ Logging Library</b></p>
</div>
<br>
- [Introduction](#introduction)
- [Documentation](#documentation)
- [Features](#features)
- [Caveats](#caveats)
- [Performance](#performance)
- [Quick Start](#quick-start)
- [CMake Integration](#cmake-integration)
- [Design](#design)
- [License](#license)
| homebrew | vcpkg | conan |
|:--------------------:|:---------------------:|:-----------------:|
| `brew install quill` | `vcpkg install quill` | `quill/[>=1.2.3]` |
## Introduction
Quill is a high-performance, cross-platform logging library designed for C++17 and onwards.
Quill is a production-ready logging library that has undergone extensive unit testing. It has been successfully utilized
in production environments, including financial trading applications, providing high-performance and reliable logging
capabilities.
## Documentation
For detailed documentation and usage instructions, please visit
the [Quill Documentation on Read the Docs](http://quillcpp.readthedocs.io/). It provides comprehensive information on
how to integrate and utilize Quill in your C++ applications.
Additionally, you can explore the [examples](http://github.com/odygrd/quill/tree/master/examples) folder in the Quill
repository on GitHub. These examples serve as valuable resources to understand different usage scenarios and demonstrate
the capabilities of the library.
## Features
- **Low Latency Logging**: Achieve fast logging performance with low latency. Refer to
the [Benchmarks](http://github.com/odygrd/quill#performance) for more details.
- **Asynchronous logging**: Log arguments and messages are formatted in a backend logging thread, effectively offloading
the formatting overhead from the critical path.
- **Custom Formatters**: Customize log formatting based on user-defined patterns.
Explore [Formatters](http://quillcpp.readthedocs.io/en/latest/tutorial.html#formatters) for further details.
- **Flexible Timestamp Generation**: Choose between rdtsc, chrono, or custom clocks (useful for simulations) for
log message timestamp generation.
- **Log Stack Traces**: Store log messages in a ring buffer and display them later in response to a higher severity log
statement or on demand. Refer
to [Backtrace Logging](http://quillcpp.readthedocs.io/en/latest/tutorial.html#backtrace-logging) for more information.
- **Multiple Logging Sinks**: Utilize various logging targets, including:
- Console logging with color support.
- File logging.
- Rotating log files based on time or size.
- JSON logging.
- Custom sinks.
- **Log Message Filtering**: Apply filters to selectively process log messages. Learn more
about [Filters](http://quillcpp.readthedocs.io/en/latest/tutorial.html#filters).
- **Structured Logging**: Generate JSON structured logs.
See [Structured-Log](http://quillcpp.readthedocs.io/en/latest/tutorial.html#json-log) for details.
- **Blocking or Dropping Message Modes**: Choose between `blocking` or `dropping` message modes in the library.
In `blocking` mode, the hot threads pause and wait when the queue is full until space becomes available, ensuring no
message loss but introducing potential latency. In `dropping` mode, log messages beyond the queue's capacity may be
dropped to prioritize low latency. The library provides reports on dropped messages, queue reallocations, and blocked
hot threads for monitoring purposes.
- **Queue Types**: The library supports different types of queues for transferring logs from the hot path to the backend
thread: bounded queues with a fixed capacity and unbounded queues that start small and can dynamically grow.
- **Wide Character Support**: Wide strings compatible with ASCII encoding are supported, applicable to Windows only.
Additionally, there is support for logging STL containers consisting of wide strings. Note that chaining STL types,
such as `std::vector<std::vector<std::wstring>>` is not supported for wide strings.
- **Ordered Log Statements**: Log statements are ordered by timestamp even when produced by different threads,
facilitating easier debugging of multithreaded applications.
- **Compile-Time Log Level Stripping**: Completely strip out log levels at compile time, reducing `if` branches.
- **Clean and Warning-Free Codebase**: Ensure a clean and warning-free codebase, even with high compiler warning levels.
- **Crash-Safe Behavior**: Benefit from crash-safe behavior with a built-in signal handler.
- **Type-Safe API**: Type safe api using the excellent [{fmt}](http://github.com/fmtlib/fmt) library.
- **Huge Pages**: Benefit from support for huge pages on the hot path. This feature allows for improved performance and
efficiency.
## Caveats
Quill may not work well with `fork()` since it spawns a background thread and `fork()` doesn't work well
with multithreading.
If your application uses `fork()` and you want to log in the child processes as well, you should call
`quill::start()` after the `fork()` call. Additionally, you should ensure that you write to different
files in the parent and child processes to avoid conflicts.
For example :
```c++
#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/FileSink.h"
int main()
{
// DO NOT CALL THIS BEFORE FORK
// quill::Backend::start();
if (fork() == 0)
{
quill::Backend::start();
// Get or create a handler to the file - Write to a different file
auto file_sink = quill::Frontend::create_or_get_sink<quill::FileSink>(
"child.log");
quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(file_sink));
QUILL_LOG_INFO(logger, "Hello from Child {}", 123);
}
else
{
quill::Backend::start();
// Get or create a handler to the file - Write to a different file
auto file_sink = quill::Frontend::create_or_get_sink<quill::FileSink>(
"parent.log");
quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(file_sink));
QUILL_LOG_INFO(logger, "Hello from Parent {}", 123);
}
}
```
## Performance
### Latency
The results presented in the tables below are measured in `nanoseconds (ns)`.
#### Logging Numbers
The following message is logged 100'000 times for each thread:
`LOG_INFO(logger, "Logging int: {}, int: {}, double: {}", i, j, d)`.
##### 1 Thread Logging
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 7 | 7 | 8 | 8 | 9 | 10 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 8 | 8 | 9 | 9 | 10 | 13 |
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 8 | 8 | 9 | 9 | 10 | 13 |
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 8 | 8 | 9 | 9 | 10 | 13 |
| [PlatformLab NanoLog](http://github.com/PlatformLab/NanoLog) | 11 | 12 | 13 | 14 | 15 | 20 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 21 | 21 | 22 | 24 | 28 | 57 |
| [Reckless](http://github.com/mattiasflodin/reckless) | 41 | 45 | 47 | 48 | 49 | 69 |
| [Iyengar NanoLog](http://github.com/Iyengar111/NanoLog) | 51 | 54 | 63 | 81 | 113 | 160 |
| [spdlog](http://github.com/gabime/spdlog) | 148 | 153 | 159 | 163 | 169 | 176 |
| [g3log](http://github.com/KjellKod/g3log) | 1192 | 1282 | 1363 | 1440 | 1624 | 1802 |
##### 4 Threads Logging Simultaneously
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 7 | 8 | 9 | 9 | 10 | 13 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 8 | 8 | 9 | 9 | 11 | 13 |
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 8 | 9 | 10 | 10 | 11 | 13 |
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 9 | 9 | 10 | 11 | 12 | 15 |
| [PlatformLab NanoLog](http://github.com/PlatformLab/NanoLog) | 12 | 13 | 13 | 14 | 15 | 19 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 21 | 21 | 22 | 22 | 29 | 62 |
| [Reckless](http://github.com/mattiasflodin/reckless) | 42 | 46 | 47 | 48 | 54 | 78 |
| [Iyengar NanoLog](http://github.com/Iyengar111/NanoLog) | 53 | 62 | 93 | 122 | 150 | 216 |
| [spdlog](http://github.com/gabime/spdlog) | 209 | 236 | 276 | 304 | 409 | 700 |
| [g3log](http://github.com/KjellKod/g3log) | 1344 | 1415 | 1489 | 1557 | 1815 | 5855 |
#### Logging Large Strings
The following message is logged 100'000 times for each thread:
`LOG_INFO(logger, "Logging int: {}, int: {}, string: {}", i, j, large_string)`.
The large string used in the log message is over 35 characters to prevent the short string optimization
of `std::string`.
##### 1 Thread Logging
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 10 | 12 | 13 | 13 | 14 | 16 |
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 11 | 12 | 13 | 14 | 15 | 17 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 11 | 12 | 13 | 14 | 15 | 17 |
| [PlatformLab NanoLog](http://github.com/PlatformLab/NanoLog) | 13 | 14 | 15 | 15 | 17 | 19 |
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 13 | 14 | 16 | 16 | 17 | 21 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 22 | 23 | 23 | 25 | 30 | 59 |
| [Iyengar NanoLog](http://github.com/Iyengar111/NanoLog) | 52 | 55 | 64 | 83 | 114 | 160 |
| [Reckless](http://github.com/mattiasflodin/reckless) | 102 | 122 | 134 | 137 | 143 | 153 |
| [spdlog](http://github.com/gabime/spdlog) | 120 | 123 | 127 | 130 | 138 | 145 |
| [g3log](http://github.com/KjellKod/g3log) | 955 | 1049 | 1129 | 1190 | 1351 | 1539 |
##### 4 Threads Logging Simultaneously
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 11 | 12 | 13 | 15 | 16 | 18 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 11 | 12 | 13 | 15 | 16 | 18 |
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 12 | 13 | 14 | 15 | 16 | 19 |
| [PlatformLab NanoLog](http://github.com/PlatformLab/NanoLog) | 13 | 15 | 15 | 16 | 17 | 20 |
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 14 | 16 | 17 | 18 | 19 | 22 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 23 | 24 | 24 | 25 | 31 | 62 |
| [Iyengar NanoLog](http://github.com/Iyengar111/NanoLog) | 53 | 60 | 92 | 121 | 149 | 212 |
| [Reckless](http://github.com/mattiasflodin/reckless) | 101 | 121 | 133 | 136 | 143 | 160 |
| [spdlog](http://github.com/gabime/spdlog) | 186 | 215 | 266 | 297 | 381 | 641 |
| [g3log](http://github.com/KjellKod/g3log) | 1089 | 1164 | 1252 | 1328 | 1578 | 5563 |
#### Logging Complex Types
The following message is logged 100'000 times for each thread:
`LOG_INFO(logger, "Logging int: {}, int: {}, vector: {}", i, j, v)`.
Logging `std::vector<std::string> v` containing 16 large strings, each ranging from 50 to 60 characters.
The strings used in the log message are over 35 characters to prevent the short string optimization of `std::string`.
##### 1 Thread Logging
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 52 | 54 | 56 | 58 | 60 | 63 |
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 53 | 55 | 57 | 59 | 62 | 103 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 66 | 70 | 79 | 81 | 84 | 91 |
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 632 | 651 | 676 | 698 | 737 | 1049 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 724 | 752 | 776 | 789 | 814 | 857 |
| [spdlog](http://github.com/gabime/spdlog) | 6242 | 6331 | 6438 | 6523 | 6782 | 7341 |
##### 4 Threads Logging Simultaneously
| Library | 50th | 75th | 90th | 95th | 99th | 99.9th |
|---------------------------------------------------------------------|:----:|:----:|:----:|:----:|:----:|:------:|
| [Quill v4.1 Bounded Dropping Queue](http://github.com/odygrd/quill) | 55 | 57 | 59 | 61 | 64 | 77 |
| [MS BinLog](http://github.com/Morgan-Stanley/binlog) | 70 | 74 | 83 | 85 | 88 | 102 |
| [Quill v4.1 Unbounded Queue](http://github.com/odygrd/quill) | 92 | 100 | 110 | 118 | 135 | 157 |
| [Quill v3.8 Unbounded Queue](http://github.com/odygrd/quill) | 674 | 694 | 736 | 762 | 805 | 884 |
| [fmtlog](http://github.com/MengRao/fmtlog) | 789 | 813 | 833 | 845 | 872 | 908 |
| [spdlog](http://github.com/gabime/spdlog) | 6500 | 6596 | 6724 | 6848 | 7560 | 9036 |
The benchmark was conducted on `Linux RHEL 9` with an `Intel Core i5-12600` at 4.8 GHz.
The cpus are isolated on this system and each thread was pinned to a different CPU. `GCC 13.1` was used as the compiler.
The benchmark methodology involved logging 20 messages in a loop, calculating and storing the average latency for those
20 messages, then waiting around ~2 milliseconds, and repeating this process for a specified number of iterations.
_In the `Quill Bounded Dropping` benchmarks, the dropping queue size is set to `262,144` bytes, which is double the
default size of `131,072` bytes._
You can find the benchmark code on the [logger_benchmarks](http://github.com/odygrd/logger_benchmarks) repository.
### Throughput
The maximum throughput is measured by determining the maximum number of log messages the backend logging thread can
write to the log file per second.
When measured on the same system as the latency benchmarks mentioned above the average throughput of the backend
logging thread is `4.56 million msgs/sec`
While the primary focus of the library is not on throughput, it does provide efficient handling of log messages across
multiple threads. The backend logging thread, responsible for formatting and ordering log messages from hot threads,
ensures that all queues are emptied on a high priority basis. The backend thread internally buffers the log messages
and then writes them later when the caller thread queues are empty or when a predefined limit,
`backend_thread_transit_events_soft_limit`, is reached. This approach prevents the need for allocating new queues
or dropping messages on the hot path.
Comparing throughput with other logging libraries in an asynchronous logging scenario has proven challenging. Some
libraries may drop log messages, resulting in smaller log files than expected, while others only offer asynchronous
flush, making it difficult to determine when the logging thread has finished processing all messages.
In contrast, Quill provides a blocking flush log guarantee, ensuring that every log message from the hot threads up to
that point is flushed to the file.
For benchmarking purposes, you can find the
code [here](https://github.com/odygrd/quill/blob/master/benchmarks/backend_throughput/quill_backend_throughput.cpp).
### Compilation Time
Compile times are measured using `clang 15` and for `Release` build.
Below, you can find the additional headers that the library will include when you need to log, following
the [recommended_usage](https://github.com/odygrd/quill/blob/master/examples/recommended_usage/recommended_usage.cpp)
example
![quill_v4_1_compiler_profile.speedscope.png](docs%2Fquill_v4_1_compiler_profile.speedscope.png)
There is also a compile-time benchmark measuring the compilation time of 2000 auto-generated log statements with
various arguments. You can find
it [here](https://github.com/odygrd/quill/blob/master/benchmarks/compile_time/compile_time_bench.cpp). It takes approximately 30
seconds to compile.
![quill_v4_compiler_bench.speedscope.png](docs%2Fquill_v4_compiler_bench.speedscope.png)
## Quick Start
```c++
#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/FileSink.h"
int main()
{
// Start the backend thread
quill::Backend::start();
// Log to file
auto file_sink = quill::Frontend::create_or_get_sink<quill::FileSink>(
"example_file_logging.log");
quill::Logger* logger =
quill::Frontend::create_or_get_logger("root", std::move(file_sink));
// set the log level of the logger to trace_l3 (default is info)
logger->set_log_level(quill::LogLevel::TraceL3);
LOG_INFO(logger, "Welcome to Quill!");
LOG_ERROR(logger, "An error message. error code {}", 123);
LOG_WARNING(logger, "A warning message.");
LOG_CRITICAL(logger, "A critical error.");
LOG_DEBUG(logger, "Debugging foo {}", 1234);
LOG_TRACE_L1(logger, "{:>30}", "right aligned");
LOG_TRACE_L2(logger, "Positional arguments are {1} {0} ", "too", "supported");
LOG_TRACE_L3(logger, "Support for floats {:03.2f}", 1.23456);
}
```
```c++
#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/ConsoleSink.h"
int main()
{
// Start the backend thread
quill::Backend::start();
// Frontend
auto console_sink = quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1");
quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(console_sink));
// Change the LogLevel to print everything
logger->set_log_level(quill::LogLevel::TraceL3);
LOG_INFO(logger, "Welcome to Quill!");
LOG_ERROR(logger, "An error message. error code {}", 123);
LOG_WARNING(logger, "A warning message.");
LOG_CRITICAL(logger, "A critical error.");
LOG_DEBUG(logger, "Debugging foo {}", 1234);
LOG_TRACE_L1(logger, "{:>30}", "right aligned");
LOG_TRACE_L2(logger, "Positional arguments are {1} {0} ", "too", "supported");
LOG_TRACE_L3(logger, "Support for floats {:03.2f}", 1.23456);
}
```
### Output
[![Screenshot-2020-08-14-at-01-09-43.png](http://i.postimg.cc/02Vbt8LH/Screenshot-2020-08-14-at-01-09-43.png)](http://postimg.cc/LnZ95M4z)
## CMake-Integration
#### External
##### Building and Installing Quill
```
git clone http://github.com/odygrd/quill.git
mkdir cmake_build
cd cmake_build
cmake ..
make install
```
Note: To install in custom directory invoke cmake with `-DCMAKE_INSTALL_PREFIX=/quill/install-dir/`
Then use the library from a CMake project, you can locate it directly with `find_package()`
##### Directory Structure
```
my_project/
├── CMakeLists.txt
├── main.cpp
```
##### CMakeLists.txt
```cmake
# Set only if needed - quill was installed under a custom non-standard directory
set(CMAKE_PREFIX_PATH /test_quill/usr/local/)
find_package(quill REQUIRED)
# Linking your project against quill
add_executable(example main.cpp)
target_link_libraries(example PUBLIC quill::quill)
```
#### Embedded
To embed the library directly, copy the source [folder](http://github.com/odygrd/quill/tree/master/quill/quill) to your
project and call `add_subdirectory()` in your `CMakeLists.txt` file
##### Directory Structure
```
my_project/
├── quill/ (source folder)
├── CMakeLists.txt
├── main.cpp
```
##### CMakeLists.txt
```cmake
cmake_minimum_required(VERSION 3.1.0)
project(my_project)
set(CMAKE_CXX_STANDARD 17)
add_subdirectory(quill)
add_executable(my_project main.cpp)
target_link_libraries(my_project PUBLIC quill::quill)
```
#### Building Quill for Android NDK
To build Quill for Android NDK add the following `CMake` flags when configuring the build:
```
-DQUILL_NO_THREAD_NAME_SUPPORT:BOOL=ON
```
## Design
### Frontend (caller-thread)
When invoking a `LOG_` macro:
1. Creates a static constexpr metadata object to store `Metadata` such as the format string and source location.
2. Pushes the data SPSC lock-free queue. For each log message, the following variables are pushed
| Variable | Description |
|------------|:--------------------------------------------------------------------------------------------------------------:|
| timestamp | Current timestamp |
| Metadata* | Pointer to metadata information |
| Logger* | Pointer to the logger instance |
| DecodeFunc | A pointer to a templated function containing all the log message argument types, used for decoding the message |
| Args... | A serialized binary copy of each log message argument that was passed to the `LOG_` macro |
### Backend
Consumes each message from the SPSC queue, retrieves all the necessary information and then formats the message.
Subsequently, forwards the log message to all Sinks associated with the Logger.
![design.jpg](docs%2Fdesign.jpg)
## License
Quill is licensed under the [MIT License](http://opensource.org/licenses/MIT)
Quill depends on third party libraries with separate copyright notices and license terms.
Your use of the source code for these subcomponents is subject to the terms and conditions of the following licenses.
- ([MIT License](http://opensource.org/licenses/MIT)) {fmt} (http://github.com/fmtlib/fmt/blob/master/LICENSE.rst)
- ([MIT License](http://opensource.org/licenses/MIT)) doctest (http://github.com/onqtam/doctest/blob/master/LICENSE.txt)
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