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: succeed_matcher.go
    path of file: ./repos/kubeedge/vendor/github.com/onsi/gomega/matchers
    
    the code of the file until where you have to start completion: package matchers

import (
	"errors"
	"fmt"

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

type formattedGomegaError interface {
	FormattedGomegaError() 
    
func (matcher *SucceedMatcher) Match(actual interface{}) (success bool, err error) {
	// is purely nil?
	if actual == nil {
		return true, nil
	}

	// must be an 'error' type
	if !isError(actual) {
		return false, fmt.Errorf("Expected an error-type.  Got:\n%s", format.Object(actual, 1))
	}

	// must be nil (or a pointer to a nil)
	return isNil(actual), nil
}