variable : LEFT_BRACE LITERAL EQUALS unbound_segments RIGHT_BRACE
                    | LEFT_BRACE LITERAL RIGHT_BRACE

def p_variable(self, p):
        """variable : LEFT_BRACE LITERAL EQUALS unbound_segments RIGHT_BRACE
                    | LEFT_BRACE LITERAL RIGHT_BRACE"""
        p[0] = [_Segment(_BINDING, p[2])]
        if len(p) > 4:
            p[0].extend(p[4])
        else:
            p[0].append(_Segment(_TERMINAL, '*'))
            self.segment_count += 1
        p[0].append(_Segment(_END_BINDING, ''))