class_docstr: Just a collection of attributes that describes an extension
  module and everything needed to build it (hopefully in a portable
  way, but there are hooks that let you be as unportable as you need).
  
  Instance attributes:
    name : string
      the full name of the extension, including any packages -- ie.
      *not* a filename or pathname, but Python dotted name
    sources : [string]
      list of source filenames, relative to the distribution root
      (where the setup script lives), in Unix form (slash-separated)
      for portability.  Source files may be C, C++, SWIG (.i),
      platform-specific resource files, or whatever else is recognized
      by the "build_ext" command as source for a Python extension.
    include_dirs : [string]
      list of directories to search for C/C++ header files (in Unix
      form for portability)
    define_macros : [(name : string, value : string|None)]
      list of macros to define; each macro is defined using a 2-tuple,
      where 'value' is either the string to define it to or None to
      define it without a particular value (equivalent of "#define
      FOO" in source or -DFOO on Unix C compiler command line)
    undef_macros : [string]
      list of macros to undefine explicitly
    library_dirs : [string]
      list of directories to search for C/C++ libraries at link time
    libraries : [string]
      list of library names (not filenames or paths) to link against
    runtime_library_dirs : [string]
      list of directories to search for C/C++ libraries at run time
      (for shared extensions, this is when the extension is loaded)
    extra_objects : [string]
      list of extra files to link with (eg. object files not implied
      by 'sources', static library that must be explicitly specified,
      binary resource files, etc.)
    extra_compile_args : [string]
      any extra platform- and compiler-specific information to use
      when compiling the source files in 'sources'.  For platforms and
      compilers where "command line" makes sense, this is typically a
      list of command-line arguments, but for other platforms it could
      be anything.
    extra_link_args : [string]
      any extra platform- and compiler-specific information to use
      when linking object files together to create the extension (or
      to create a new static Python interpreter).  Similar
      interpretation as for 'extra_compile_args'.
    export_symbols : [string]
      list of symbols to be exported from a shared extension.  Not
      used on all platforms, and not generally necessary for Python
      extensions, which typically export exactly one symbol: "init" +
      extension_name.
    swig_opts : [string]
      any extra options to pass to SWIG if a source file has the .i
      extension.
    depends : [string]
      list of files that the extension depends on
    language : string
      extension language (i.e. "c", "c++", "objc"). Will be detected
      from the source extensions if not provided.
    optional : boolean
      specifies that a build failure in the extension should not abort the
      build process, but simply not install the failing extension.
code: def __init__(
      self,
      name,
      sources,
      include_dirs=None,
      define_macros=None,
      undef_macros=None,
      library_dirs=None,
      libraries=None,
      runtime_library_dirs=None,
      extra_objects=None,
      extra_compile_args=None,
      extra_link_args=None,
      export_symbols=None,
      swig_opts=None,
      depends=None,
      language=None,
      optional=None,
      **kw,  # To catch unknown keywords
  ):
      if not isinstance(name, str):
          raise AssertionError("'name' must be a string")
      if not (
          isinstance(sources, list)
          and all(isinstance(v, str) for v in sources)
      ):
          raise AssertionError("'sources' must be a list of strings")
  
      self.name = name
      self.sources = sources
      self.include_dirs = include_dirs or []
      self.define_macros = define_macros or []
      self.undef_macros = undef_macros or []
      self.library_dirs = library_dirs or []
      self.libraries = libraries or []
      self.runtime_library_dirs = runtime_library_dirs or []
      self.extra_objects = extra_objects or []
      self.extra_compile_args = extra_compile_args or []
      self.extra_link_args = extra_link_args or []
      self.export_symbols = export_symbols or []
      self.swig_opts = swig_opts or []
      self.depends = depends or []
      self.language = language
      self.optional = optional
  
      # If there are unknown keyword options, warn about them
      if len(kw) > 0:
          options = [repr(option) for option in kw]
          options = ", ".join(sorted(options))
          msg = "Unknown Extension options: %s" % options
          warnings.warn(msg)
  
imports: import os
  import re
  import warnings
label_desc: Use image node_id 1 to create a new Extension object  with example: obj = Extension(name, sources, include_dirs, define_macros, undef_macros, library_dirs, libraries, runtime_library_dirs, extra_objects, extra_compile_args, extra_link_args, export_symbols, swig_opts, depends, language, optional)