code: def _preprocess(csource):
      # First, remove the lines of the form '#line N "filename"' because
      # the "filename" part could confuse the rest
      csource, line_directives = _remove_line_directives(csource)
  
      # Remove comments.  NOTE: this only work because the cdef() section
      # should not contain any string literals (except in line directives)!
      def replace_keeping_newlines(m):
          return " " + m.group().count("\n") * "\n"
  
      csource = _r_comment.sub(replace_keeping_newlines, csource)
      # Remove the "#define FOO x" lines
      macros = {}
      for match in _r_define.finditer(csource):
          macroname, macrovalue = match.groups()
          macrovalue = macrovalue.replace("\\\n", "").strip()
          macros[macroname] = macrovalue
      csource = _r_define.sub("", csource)
      #
      if pycparser.__version__ < "2.14":
          csource = _workaround_for_old_pycparser(csource)
      #
      # BIG HACK: replace WINAPI or __stdcall with "volatile const".
      # It doesn't make sense for the return type of a function to be
      # "volatile volatile const", so we abuse it to detect __stdcall...
      # Hack number 2 is that "int(volatile *fptr)();" is not valid C
      # syntax, so we place the "volatile" before the opening parenthesis.
      csource = _r_stdcall2.sub(" volatile volatile const(", csource)
      csource = _r_stdcall1.sub(" volatile volatile const ", csource)
      csource = _r_cdecl.sub(" ", csource)
      #
      # Replace `extern "Python"` with start/end markers
      csource = _preprocess_extern_python(csource)
      #
      # Now there should not be any string literal left; warn if we get one
      _warn_for_string_literal(csource)
      #
      # Replace "[...]" with "[__dotdotdotarray__]"
      csource = _r_partial_array.sub("[__dotdotdotarray__]", csource)
      #
      # Replace "...}" with "__dotdotdotNUM__}".  This construction should
      # occur only at the end of enums; at the end of structs we have "...;}"
      # and at the end of vararg functions "...);".  Also replace "=...[,}]"
      # with ",__dotdotdotNUM__[,}]": this occurs in the enums too, when
      # giving an unknown value.
      matches = list(_r_partial_enum.finditer(csource))
      for number, match in enumerate(reversed(matches)):
          p = match.start()
          if csource[p] == "=":
              p2 = csource.find("...", p, match.end())
              assert p2 > p
              csource = "%s,__dotdotdot%d__ %s" % (
                  csource[:p],
                  number,
                  csource[p2 + 3 :],
              )
          else:
              assert csource[p : p + 3] == "..."
              csource = "%s __dotdotdot%d__ %s" % (
                  csource[:p],
                  number,
                  csource[p + 3 :],
              )
      # Replace "int ..." or "unsigned long int..." with "__dotdotdotint__"
      csource = _r_int_dotdotdot.sub(" __dotdotdotint__ ", csource)
      # Replace "float ..." or "double..." with "__dotdotdotfloat__"
      csource = _r_float_dotdotdot.sub(" __dotdotdotfloat__ ", csource)
      # Replace all remaining "..." with the same name, "__dotdotdot__",
      # which is declared with a typedef for the purpose of C parsing.
      csource = csource.replace("...", " __dotdotdot__ ")
      # Finally, put back the line directives
      csource = _put_back_line_directives(csource, line_directives)
      return csource, macros
  
imports: from .None import model
  from .commontypes import COMMON_TYPES, resolve_common_type
  from .error import FFIError, CDefError
  import weakref, re, sys
label_desc: Use image node_id 9 for calling a global function with example usage: _preprocess(csource) and returns: csource,  macros, unknown