code: def is_email_address(string):
      
      return string and isinstance(string, base_string) \
          and REGEX_PATTERN_EMAIL_ADDRESS.match(string.strip().lower())
docs: Check whether the specified string corresponds to an email address.
  
      @param string: a string that is expected to be an email address.
  
      @return: ``True`` if the string corresponds to an email address,
          ``False`` otherwise.