Add support for additional arguments

[stackoverfloweth]

When mapping some models it would be nice to support other required arguments in addition to source. This could enable something like mapping a single model from 2 source models or including a parent models id.

[pleek91]

I think this use case can easily be solved by making source an object of the required pieces.

Ive used that pattern a decent bit and feels nice.

Do you have a use case in mind where that doesn't feel right to you?

My guess is you're thinking a source that can be mapped to multiple destinations but for one particular mapping an additional piece is required.

Curious how much complexity that would add for something we can leave for userland implementation.