Returns the lower extent of the dimensions in args.

        .. code-block:: python

            t_ex, bl_ex, ch_ex = cube.dim_lower_extent('ntime', 'nbl', 'nchan')

        or

        .. code-block:: python

            t_ex, bl_ex, ch_ex, src_ex = cube.dim_lower_extent('ntime,nbl:nchan nsrc')

def dim_lower_extent(self, *args, **kwargs):
        """
        Returns the lower extent of the dimensions in args.

        .. code-block:: python

            t_ex, bl_ex, ch_ex = cube.dim_lower_extent('ntime', 'nbl', 'nchan')

        or

        .. code-block:: python

            t_ex, bl_ex, ch_ex, src_ex = cube.dim_lower_extent('ntime,nbl:nchan nsrc')
        """

        # The lower extent of any integral dimension is 0 by default
        args = tuple(0 if isinstance(a, (int, np.integer))
            else a for a in args)
        return self._dim_attribute('lower_extent', *args, **kwargs)