Assume no return if closing parens are not present

[DefiDebauchery]

More of a nice to have, but I often forget to add return parens for methods that don't have them, especially when I'm just simulating a call for validity. For instance, Safe's execTransaction(...) doesn't actually return anything, but I run it to ensure it won't revert.

I tried looking into the code and couldn't figure out the best way to do this, so I was curious if there was a good way of accomplishing this. Feel free to close if this is dumb ;)

  File ".../multicall/call.py", line 70, in __init__
    returns: Optional[Iterable[Tuple[str, Optional[Callable]]]] = None,
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../multicall/signature.py", line 83, in _get_signature
    continue
  File ".../multicall/signature.py", line 91, in __init__
    return _SIGNATURES[signature]

  File ".../multicall/signature.py", line 57, in parse_signature
    start = end