   Traceback (most recent call last):
        ...
        ValueError: Use of .. or absolute path in a resource path is not allowed.

        Blank values are allowed

        >>> vrp('')
        >>> bool(warned)
        False

        Non-string values are not.

        >>> vrp(None)
        Traceback (most recent call last):
        ...
        AttributeError: ...
        Nz=Use of .. or absolute path in a resource path is not allowed.r¬