CS代考计算机代写 package sexpr

package sexpr

import (
“errors”
//”math/big” // You will need to use this package in your implementation.
)

// ErrEval is the error value returned by the Evaluator if the contains
// an invalid token.
// See also https://golang.org/pkg/errors/#New
// and // https://golang.org/pkg/builtin/#error
var ErrEval = errors.New(“eval error”)

func (expr *SExpr) Eval() (*SExpr, error) {
panic(“TODO: implement Eval”)
}