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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)