How to use the xgcm.models.mitgcm.variables.layers_grid_variables.items function in xgcm

def _make_layers_variables(layer_name):
    """Translate metadata template to actual variable metadata."""
    from .variables import layers_grid_variables
    lvars = xr.core.pycompat.OrderedDict()
    layer_num = layer_name[0]
    # should always be int
    assert isinstance(int(layer_num), int)
    layer_id = 'l' + layer_num
    for key, vals in layers_grid_variables.items():
        # replace the name template with the actual name
        # e.g. layer_NAME_bounds -> layer_1RHO_bounds
        varname = key.replace('NAME', layer_name)
        metadata = _recursively_replace(vals, 'NAME', layer_name)
        # now fix dimension
        metadata['dims'] = [metadata['dims'][0].replace('l', layer_id)]
        lvars[varname] = metadata
    return lvars