Dynamically compile implicit lambdas to the right arity

I just replaced all instances of lambda functions like `() -> ...` by `-> ...` since it seems to be a possible shortcut, but broke my code out of the blue.
It is compiled, however, to something like `lambda _: ...` which conflicts with many parts of my code, where I use `_` for other things (e.g. the `self` reference or a running variable in comprehensions).

Can you modify the code generation in a way that avoids this problem? Either a more unlikely lambda parameter (`__anonymous__function`) or something automatically generated guaranteed not to conflict?