Please answer the following question: Information:  - GNU Emacs is the most popular and most ported Emacs text editor. It was created by GNU Project founder Richard Stallman. In common with other varieties of Emacs, GNU Emacs is extensible using a Turing complete programming language. GNU Emacs has been called "the most powerful text editor available today." With proper support from the underlying system, GNU Emacs is able to display files in multiple character sets, and has been able to simultaneously display most human languages since at least 1999. Throughout its history, GNU Emacs has been a central component of the GNU project, and a flagship of the free software movement. GNU Emacs is sometimes abbreviated as GNUMACS, especially to differentiate it from other EMACS variants. The tag line for GNU Emacs is "the extensible self-documenting text editor".  - Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: requirements are turned into very specific test cases, then the software is improved to pass the new tests, only. This is opposed to software development that allows software to be added that is not proven to meet requirements.  - In software engineering, behavior-driven development (BDD) is a software development process that emerged from test-driven development (TDD). Behavior-driven development combines the general techniques and principles of TDD with ideas from domain-driven design and object-oriented analysis and design to provide software development and management teams with shared tools and a shared process to collaborate on software development.  - In software engineering, a software development methodology (also known as a system development methodology, software development life cycle, software development process, software process) is a splitting of software development work into distinct phases (or stages) containing activities with the intent of better planning and management. It is often considered a subset of the systems development life cycle. The methodology may include the pre-definition of specific deliverables and artifacts that are created and completed by a project team to develop or maintain an application.  - Software engineering (SWE) is the application of engineering to the development of software in a systematic method.  - sed ("stream editor") is a Unix utility that parses and transforms text, using a simple, compact programming language. sed was developed from 1973 to 1974 by Lee E. McMahon of Bell Labs, and is available today for most operating systems. sed was based on the scripting features of the interactive editor ed ("editor", 1971) and the earlier qed ("quick editor", 196566). sed was one of the earliest tools to support regular expressions, and remains in use for text processing, most notably with the substitution command. Other options for doing "stream editing" include AWK and Perl.  - A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains. There is a wide variety of DSLs, ranging from widely used languages for common domains, such as HTML for web pages, down to languages used by only one or a few pieces of software, such as Emacs Lisp for GNU Emacs and XEmacs. DSLs can be further subdivided by the kind of language, and include domain-specific "markup" languages, domain-specific "modeling" languages (more generally, specification languages), and domain-specific "programming" languages. Special-purpose computer languages have always existed in the computer age, but the term "domain-specific language" has become more popular due to the rise of domain-specific modeling. Simpler DSLs, particularly ones used by a single application, are sometimes informally called mini-languages.  - Domain-driven design (DDD) is an approach to software development for complex needs by connecting the implementation to an evolving model. The premise of domain-driven design is the following:  - Domain-specific modeling is a software engineering methodology for designing and developing systems, such as computer software. It involves systematic use of a domain-specific language to represent the various facets of a system.   - A specification language is a formal language in computer science used during systems analysis, requirements analysis and systems design to describe a system at a much higher level than a programming language, which is used to produce the executable code for a system.  - Emacs Lisp is a dialect of the Lisp programming language used as a scripting language by Emacs (a text editor family most commonly associated with GNU Emacs and XEmacs). It is used for implementing most of the editing functionality built into Emacs, the remainder being written in C (as is the Lisp interpreter itself). Emacs Lisp is also referred to as Elisp, although there is also an older, unrelated Lisp dialect with that name.  - HyperText Markup Language (HTML) is the standard markup language for creating web pages and web applications. With Cascading Style Sheets (CSS), and JavaScript, it forms a triad of cornerstone technologies for the World Wide Web. Web browsers receive HTML documents from a webserver or from local storage and render them into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for the appearance of the document.  - Object-oriented analysis and design (OOAD) is a popular technical approach for analyzing, designing an application, system, or business by applying the object-oriented paradigm and visual modeling throughout the development life cycles to foster better stakeholder communication and product quality.  - RSpec is a behavior - driven development ( BDD ) framework for the Ruby programming language , inspired by JBehave . It contains its own mocking framework that is fully integrated into the framework based upon JMock . The framework can be considered a domain - specific language ( DSL ) and resembles a natural language specification .  - XEmacs is a graphical- and console-based text editor which runs on almost any Unix-like operating system as well as Microsoft Windows. XEmacs is a fork, based on a version of GNU Emacs from the late 1980s. Any user can download, use, and modify XEmacs as free software available under the GNU General Public License version 2 or any later version.    Given the information above, choose from the list below the object entity that exhibits the relation 'instance of' with the subject 'rspec'.  Choices: - application  - behavior  - bell  - communication  - computer language  - cycle  - definition  - design  - dialect  - editor  - emacs  - executable  - fork  - founder  - free software  - human  - interpreter  - language  - line  - markup language  - microsoft windows  - model  - multimedia  - name  - object  - operating system  - process  - product  - programming  - programming language  - quality  - science  - single  - software  - software development  - specification  - standard  - stream  - structure  - style  - system  - team  - term  - test  - text  - text editor  - variety  - web page  - work
A:
free software