# Check for method
The equivalent of PHP's `method_exists`. See [this stackoverflow](https://stackoverflow.com/questions/5268404/what-is-the-fastest-way-to-check-if-a-class-has-a-function-defined)

```py
invert_op = getattr(self, "invert_op", None)
if callable(invert_op):
    invert_op(self.path.parent_op)
```