A common way to create a DGAlgebraMap is via liftToDGMap.
The object DGAlgebraMap is a type, with ancestor classes MutableHashTable < HashTable < Thing.
The source of this document is in /build/reproducible-path/macaulay2-1.25.06+ds/M2/Macaulay2/packages/DGAlgebras.m2:2868:0.