code: def _read_pyc(source, pyc):
      
      try:
          fp = open(pyc, "rb")
      except IOError:
          return None
      try:
          try:
              mtime = int(os.stat(source).st_mtime)
              data = fp.read(8)
          except EnvironmentError:
              return None
          # Check for invalid or out of date pyc file.
          if (len(data) != 8 or data[:4] != imp.get_magic() or
                  struct.unpack("<l", data[4:])[0] != mtime):
              return None
          co = marshal.load(fp)
          if not isinstance(co, types.CodeType):
              # That's interesting....
              return None
          return co
      finally:
          fp.close()
docs: Possibly read a pytest pyc containing rewritten code.
  
      Return rewritten code if successful or None if not.