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: namespace.go
    path of file: ./repos/grype/grype/db/v4/namespace/cpe
    
    the code of the file until where you have to start completion: package cpe

import (
	"errors"
	"fmt"
	"strings"

	"github.com/anchore/grype/grype/db/v4/pkg/resolver"
	"github.com/anchore/grype/grype/db/v4/pkg/resolver/stock"
)
    
func FromString(namespaceStr string) (*Namespace, error) {
	if namespaceStr == "" {
		return nil, errors.New("unable to create CPE namespace from empty string")
	}

	components := strings.Split(namespaceStr, ":")

	if len(components) != 2 {
		return nil, fmt.Errorf("unable to create CPE namespace from %s: incorrect number of components", namespaceStr)
	}

	if components[1] != ID {
		return nil, fmt.Errorf("unable to create CPE namespace from %s: type %s is incorrect", namespaceStr, components[1])
	}

	return NewNamespace(components[0]), nil
}