An abstract `~collections.abc.Mapping` for use when sharing a
map between C++ and Python.
For compatibility with C++, ``GenericMap`` has the following
restrictions:
- all keys must be of the same type
- values must be built-in types or subclasses of
`lsst.afw.typehandling.Storable`. Almost any user-defined class in
C++ or Python can have `~lsst.afw.typehandling.Storable` as a mixin.
As a safety precaution, `~lsst.afw.typehandling.Storable` objects that are
added from C++ may be copied when you retrieve them from Python, making it
impossible to modify them in-place. This issue does not affect objects that
are added from Python, or objects that are always passed by
:cpp:class:`shared_ptr` in C++.
Definition at line 30 of file _GenericMap.py.