def get(self, tag, default=None):
        """Get a metadata value.

        Each metadata value is referenced by a ``tag`` -- a short
        string such as ``'xlen'`` or ``'audit'``. In the sidecar file
        these tag names are prepended with ``'Xmp.pyctools.'``, which
        corresponds to a custom namespace in the XML file.

        :param str tag: The tag name.

        :returns: The metadata value associated with ``tag``.

        :rtype: :py:class:`str`

        """
        full_tag = 'Xmp.pyctools.' + tag
        if full_tag in self.data:
            return self.data[full_tag]
        return default
Get a metadata value.

        Each metadata value is referenced by a ``tag`` -- a short
        string such as ``'xlen'`` or ``'audit'``. In the sidecar file
        these tag names are prepended with ``'Xmp.pyctools.'``, which
        corresponds to a custom namespace in the XML file.

        :param str tag: The tag name.

        :returns: The metadata value associated with ``tag``.

        :rtype: :py:class:`str`