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/devspace/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 of one parameter that returns one value and an optional error
	Matcher   types.GomegaMatcher

	// cached value
	transformArgType reflect.Type

	// state
	transformedValue interface{}
}

// reflect.Type for error
var errorT = reflect.TypeOf((*error)(nil)).Elem()

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 
    
func (m *WithTransformMatcher) Match(actual interface{}) (bool, error) {
	// prepare a parameter to pass to the Transform function
	var param reflect.Value
	if actual != nil && reflect.TypeOf(actual).AssignableTo(m.transformArgType) {
		// The dynamic type of actual is compatible with the transform argument.
		param = reflect.ValueOf(actual)

	} else if actual == nil && m.transformArgType.Kind() == reflect.Interface {
		// The dynamic type of actual is unknown, so there's no way to make its
		// reflect.Value. Create a nil of the transform argument, which is known.
		param = reflect.Zero(m.transformArgType)

	} else {
		return false, fmt.Errorf("Transform function expects '%s' but we have '%T'", m.transformArgType, actual)
	}

	// call the Transform function with `actual`
	fn := reflect.ValueOf(m.Transform)
	result := fn.Call([]reflect.Value{param})
	if len(result) == 2 {
		if !result[1].IsNil() {
			return false, fmt.Errorf("Transform function failed: %s", result[1].Interface().(error).Error())
		}
	}
	m.transformedValue = result[0].Interface() // expect exactly one value

	return m.Matcher.Match(m.transformedValue)
}