func ProjectID(p string) Option {
	return func(o *Options) {
		o.ProjectID = p
	}
}
ProjectID is a required Google Pub/Sub project id
package gcp
type Options struct {
	ProjectID          string
	TopicPrefix        string
	SubscriptionPrefix string
	CredentialsJSON    []byte
}
type Option func(*Options)
func newOptions(opts ...Option) Options {
	opt := Options{
		SubscriptionPrefix: "sub.",
	}
	for _, o := range opts {
		o(&opt)
	}
	return opt
}