Callback wraps a function in a Ptr giving it a 20 character unique string ID.

HandlerFrom uses reflection to return a handler from either a function or methods from a struct.

PtrsFrom collects Ptrs from walking exported struct fields, slice/array elements, map values, and pointers in a value.

RegisterPtrs will register handlers on the RespondMux for Ptrs found using PtrsFrom on the value.

SetCallers will set the Caller for any Ptrs found in the value using PtrsFrom, as well as any Ptrs encoded as maps, identifying them with the special key "$fnptr".

UnregisterPtrs will remove handlers from the RespondMux matching Ptr IDs found using PtrsFrom on the value.

Ptr represents a remote function pointer.

Args is the expected argument value for calls made to HandlerFrom handlers.