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: utils.go
    path of file: ./repos/juju/environs
    
    the code of the file until where you have to start completion: // Copyright 2014 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package environs

import (
	"net"
	"strconv"
	"time"

	"github.com/juju/errors"
	"github.com/juju/names/v5"
	"github.com/juju/utils/v3"

	"github.com/juju/juju/api"
	"github.com/juju/juju/core/instance"
	"github.com/juju/juju/core/network"
	"github.com/juju/juju/environs/context"
	"github.com/juju/juju/e
    
func CheckProviderAPI(envOrBroker BootstrapEnviron, ctx context.ProviderCallContext) error {
	var err error
	if checker, ok := envOrBroker.(CloudEndpointChecker); ok {
		err = checker.ValidateCloudEndpoint(ctx)
	} else if env, ok := envOrBroker.(CheckProvider); ok {
		// We will make a simple API call to the provider
		// to ensure the underlying substrate is ok.
		_, err = env.AllInstances(ctx)
		switch err {
		case nil, ErrPartialInstances, ErrNoInstances:
			return nil
		}
	}
	return errors.Annotate(err, "cannot make API call to provider")
}