You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: with_transform.go
    path of file: ./repos/podman/vendor/github.com/onsi/gomega/matchers
    
    the code of the file until where you have to start completion: package matchers

import (
	"fmt"
	"reflect"

	"github.com/onsi/gomega/types"
)

type WithTransformMatcher struct {
	// input
	Transform interface{} // must be a function o
    
func NewWithTransformMatcher(transform interface{}, matcher types.GomegaMatcher) *WithTransformMatcher {
	if transform == nil {
		panic("transform function cannot be nil")
	}
	txType := reflect.TypeOf(transform)
	if txType.NumIn() != 1 {
		panic("transform function must have 1 argument")
	}
	if numout := txType.NumOut(); numout != 1 {
		if numout != 2 || !txType.Out(1).AssignableTo(errorT) {
			panic("transform function must either have 1 return value, or 1 return value plus 1 error value")
		}
	}

	return &WithTransformMatcher{
		Transform:        transform,
		Matcher:          matcher,
		transformArgType: reflect.TypeOf(transform).In(0),
	}
}