'Returns the alias for this identifier or ``None``.'

def get_alias(self):

    (kw_idx, kw) = self.token_next_by(m=(T.Keyword, 'AS'))
    if (kw is not None):
        return self._get_first_name((kw_idx + 1), keywords=True)
    (_, ws) = self.token_next_by(t=T.Whitespace)
    if ((len(self.tokens) > 2) and (ws is not None)):
        return self._get_first_name(reverse=True)
