def p_configure_sentence(self, t):
        """configure_sentence : CONFIGURE VAR
                              | CONFIGURE VAR LPAREN RECIPE_BEGIN recipe RECIPE_END RPAREN"""

        if len(t) == 3:
            t[0] = configure(t[2], reference=True, line=t.lineno(1))
        else:
            t[0] = configure(t[2], t[5], line=t.lineno(1))
configure_sentence : CONFIGURE VAR
                              | CONFIGURE VAR LPAREN RECIPE_BEGIN recipe RECIPE_END RPAREN