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 __repr__(self):
      return "<%s.%s(%r) at %#x>" % (
          self.__class__.__module__,
          self.__class__.__qualname__,
          self.name,
          id(self),
      )
  
imports: import os
  import re
  import warnings
label_desc: Use image node_id 2 for calling the Extension obj's underlying member method code with example usage: obj.__repr__() and returns: unknown