Question

So I’m getting this error on a line where I have a recursive call. The line where the error occurred looks something like: return some_func(x) - .2

TypeError: unsupported operand type(s) for -: 'NoneType' and 'float'

I tried return some_func(x) - .2 and x not None and float(x) is True, and other tricks but unsuccessfully so far.

Thanks!

Answer 1

some_func(x) returns None, and you cannot subtract a float from None—that wouldn’t make any sense. Depending on your needs, you can either make sure some_func(x) never returns None (by changing the implementation of some_func), or do this:

y = some_func(x)
if y is not None:
    return y - .2
else:
    return None

The last two lines can be omitted, since functions in Python implicitly return None.