Refine assumption about groups of size 2.
Refine assumption about groups of size 2.

A group with len 2 usually behaves like a boolean. However, some
situations require both (or neither) value to be True at once.

PhilHarnish/forge,PhilHarnish/forge,PhilHarnish/forge,PhilHarnish/forge,PhilHarnish/forge,PhilHarnish/forge