// +build !solution

package once

// Once describes an object that will perform exactly one action.
type Once struct {
}

// New create Once.
func New() *Once {
	return nil
}

// Do calls the function f if and only if Do is being called for the
// first time for this instance of Once. In other words, given
// 	once := New()
// if once.Do(f) is called multiple times, only the first call will invoke f,
// even if f has a different value in each invocation. A new instance of
// Once is required for each function to execute.
//
// Do is intended for initialization that must be run exactly once.
//
// Because no call to Do returns until the one call to f returns, if f causes
// Do to be called, it will deadlock.
//
// If f panics, Do considers it to have returned; future calls of Do return
// without calling f.
//
func (o *Once) Do(f func()) {

}