Hi. I've been using this snippet for years and believe that it would be a nice addition to pathlib's functionality.

Basically, it allows constructing path relative to the current file (instead of cwd). Comes quite handy when you're working with deeply nested resources like file fixtures in tests and many other cases.

```
    @classmethod
    def relative(cls, path, depth=1):
        """
        Return path that is constructed relatively to caller file.
        """
        base = Path(sys._getframe(depth).f_code.co_filename).parent
        return (base / path).resolve()
```

To be clear, by "file", you mean python source file, or I guess .pyc file if only that exists. I can't say I've given it much thought. What about built-in modules? Or frozen modules?

I'm not sure this is a great idea. In general, we've frowned on code that uses sys._getframe, and in particular that looks arbitrarily up the stack.

At the very least, you should find out if other python implementations can use this function.

I suggest bringing this up on the python-ideas mailing list.

I am rejecting this for the reasons explained in the Github PR:

"""This seems like an extremely specific API. Perhaps you want to propose it for inclusion in pytest, but I don't think it belongs in pathlib.

(also, it's not difficult to spell out `Path(__file__)`)"""