<pre>
func (p *Point) Length() float64 {
	return math.Sqrt(p.x * p.x + p.y * p.y)
}

func (p *Point) Scale(factor float64) {
	p.x *= factor
	p.y *= factor
}
</pre>

<p>
bind the methods <code>Length</code> and <code>Scale</code>,
with receiver type <code>*Point</code>,
to the base type <code>Point</code>.
</p>

<p>

</li>
<li>
	Both types have identical structure and their element types
	unify exactly.
</li>
<li>
	Exactly one type is an <a href="#Type_inference">unbound</a>
	type parameter with a <a href="#Core_types">core type</a>,
	and that core type unifies with the other type per the
	unification rules for <code>≡<sub>A</sub></code>