The code to decide which C++ method signature to call for a set of given Python
arguments relies, among other things, on the ordering of the method overloads.
This ordering is based on the implicit conversions for a given type, roughly
speaking on the decisor code type A should be checked before type B if B could
be implicitly created by a type A object.

There must be some way to inform the convertible dependencies of a type so that
the overload decisor can use the methods properly sorted.