Hi, I have a complicated function which has enough arguments that I want to use keyword args, and I want to have some default values, and in the early stages I like to use Unitful to help me catch dimensional errors, but at other times I would like to be able to just use SI throughout and drop all the clutter of the units.

I can do that in the following way:

```
f_(a,b) = a+b # imagine a bit more complexity here!
f(a,b=1.0) = f_(a,b)
f(a::Quantity,b::Quantity = 1.0u"m") = f_(a,b)
```

and then `f(2.0e-3)`

and `f(2.0u"mm")`

both do what I would want.

I feel like there should be a way for multiple dispatch to solve this for me, but in my attempts I’ve only figured out new ways to generate a stack overflow.

[EDIT: simplified MWE]