return a `Path` from the path of caller file

def from_caller_file():
        '''return a `Path` from the path of caller file'''
        import inspect
        curframe = inspect.currentframe()
        calframe = inspect.getouterframes(curframe, 2)
        filename = calframe[1].filename
        if not os.path.isfile(filename):
            raise RuntimeError('caller is not a file')
        return Path(filename)