Fail when calling configurable functions on module import

It is very easy to make the mistake of calling a configurable when defining a default argument. In this case bind does not do anything. Consider failing the example:

In module.py

@configurable
def f(param='default'):
    return param

def g(f=f()):
    return f

In top level options

from module import f
with f.bind(param='override'):
    assert g() == 'override'

Thanks to @sstahl for reporting