goprocess.go
func WithParent(parent Process) Process {
	if parent == nil {
		panic("nil parent Process")
	}
	q := newProcess(nil)
	parent.AddChild(q)
	return q
}
func WithParent(parent Process) Process {
	if parent == nil {
		panic("nil parent Process")
	}
	q := newProcess(nil)
	parent.AddChild(q)
	return q
}
// WithParent constructs and returns a Process with a given parent.