non-interface terms must be pairwise disjoint (the pairwise intersection of the type sets must be empty).
Given a type parameter <code>P</code>:
</p>

<pre>
interface {
	P                // illegal: P is a type parameter
	int | ~P         // illegal: P is a type parameter
	~int | MyInt     // illegal: the type sets for ~int and MyInt are not disjoint (~int includes MyInt)