(self)
return [k for k, v in self._headers]
Return a list of all the message's header field names.

        These will be sorted in the order they appeared in the original
        message, or were added to the message, and may contain duplicates.
        Any fields deleted and re-inserted are always appended to the header
        list.
Return a list of all the message's header field names.
Return a list of all the message s header field names .
def keys(self):
        """Return a list of all the message's header field names.

        These will be sorted in the order they appeared in the original
        message, or were added to the message, and may contain duplicates.
        Any fields deleted and re-inserted are always appended to the header
        list.
        """
        return [k for k, v in self._headers]
def keys ( self ) : return [ k for k , v in self . _headers ]