code: def func(self, node):
          'func = "(" parameters ")" _ "->" expr'
          _, params, _, _, _, expr = node
          params = map(self.eval, params)
          def func(*args):
              env = dict(self.env.items() + zip(params, args))
              return Mini(env).eval(expr)
          return funf func(self, node):
          'func = "(" parameters ")" _ "->" expr'
          _, params, _, _, _, expr = node
          params = map(self.eval, params)
          def func(*args):
              env = dict(self.env.items() + zip(params, args))
              return Mini(env).eval(expr)
          return func
docs: func = "(" parameters ")" _ "->" expr