code: def _is_alphanum(cls, c):
          
  
          alphanum_rxc = re.compile(CPEComponentSimple._ALPHANUM_PATTERN)
          return (alphanum_rxc.match(c) is not None)
docs: Returns True if c is an uppercase letter, a lowercase letter,
          a digit or an underscore, otherwise False.
  
          :param string c: Character to check
          :returns: True if char is alphanumeric or an underscore,
              False otherwise
          :rtype: boolean
  
          TEST: a wrong character
          >>> c = "#"
          >>> CPEComponentSimple._is_alphanum(c)
          False