CheckSigs checks that each function signature implements the generic interface signature.

Implements checks that ty implements the generic interface iface.

T1Ty is the type of T1.

T2Ty is the type of T2.

T3Ty is the type of T3.

T4Ty is the type of T4.

TOTy is the type of TO.

TPTy is the type of TP.

Match is the result of Implements and CheckSigs.

Sig is a pair of functions used for validation by CheckSigs.