docs: def p_function_expr_2(self, p):
          """
          function_expr \
              : FUNCTION identifier LPAREN RPAREN LBRACE function_body RBRACE
              | FUNCTION identifier LPAREN formal_parameter_list RPAREN \
                  LBRACE function_body RBRACE
          """
          if len(p) == 8:
              p[0] = self.asttypes.FuncExpr(
                  identifier=p[2], parameters=None, elements=p[6])
          else:
              p[0] = self.asttypes.FuncExpr(
                  identifier=p[2], parameters=p[4], elements=p[7])
          p[0].setpos(p)