Guzzle is a PHP HTTP client that makes it easy to send HTTP requests and trivial to integrate with web services. Guzzle can be used with cURL, PHP's stream wrapper, sockets, and non-blocking libraries like React.

For programming/API questions related to Google Cloud Pub/Sub, which provides asynchronous messaging and ingestion services for event-driven systems and streaming analytics on the Google Cloud Platform infrastructure.

The Internet Protocol is one of the fundamental protocols used for the Internet. IPv6 is the next generation Internet Protocol, as opposed to the currently common Internet Protocol known as IPv4.

NSURLSession is the API for HTTP connections introduced in iOS 7 and OS X 10.9.

A menu item is a child element of a menu that provides the user a means to view and execute a specific application operation.

This is GitLab Runner repository, this application run tests and sends the results to GitLab CI. GitLab CI is the open-source continuous integration server that coordinates the testing.

abstract is a keyword shared by a multitude of object-oriented programming languages. Methods and classes can be marked abstract to indicate that they do not contain the full implementation of application logic and have to be extended. Abstract classes can not be instantiated and serve the purpose of providing a uniform interface for their subclasses, as well as the implementation of common methods that don't have to be reimplemented for each subclass.

A multi-index (also known as a hierarchical index) allows the manipulation of higher-dimensional data in a 2-dimensional tabular structure.

Refers to the joining of two or more elements into a single element.

"toString" or "ToString" is a major formatting method or function used in high level programming languages. It converts an Object to its string representation so that it is suitable for display.

Refers to the System.Net.Http.HttpClient library which is part of the HttpClient package on NuGet, or the .NET 4.5 library.