Allow setting a function that can modify the return value of a bound C++ function

[Keithcat1]

Pybind11 is decent at binding C-only libraries, but one thing where it can be painful is in converting C error codes into C++ exceptions. Currently the only way I know of to do this is using lambdas, but this means you have to write out the parameters of the C function you're wrapping in a lambda which is inconvenient.
What I would like to have is an ability to pass a function when making a C++ function available from Python.
This function would be called with the bound functions unconverted return value, and could either convert it to something else or consume it, such as an error code which this function would throw as a C++ exception.