The river lowered as rapidly as it rose.

It was whispered that men had been “vanished” by the Line and returned everted. Turned inside out.

I asked each person in turn, and their answers were all over the place.

Then in n>n', there is a map h:Z→Z' such that h|A=g and gf≃f'h rel A, so the diagram above is commutative up to homotopy rel A.