How to use the pyhf.workspace.Workspace function in pyhf

def calculate_CLs(bkgonly_json, signal_patch_json):
    """
    Calculate the observed CLs and the expected CLs band from a background only
    and signal patch.

    Args:
        bkgonly_json: The JSON for the background only model
        signal_patch_json: The JSON Patch for the signal model

    Returns:
        CLs_obs: The observed CLs value
        CLs_exp: List of the expected CLs value band
    """
    workspace = pyhf.workspace.Workspace(bkgonly_json)
    model = workspace.model(
        measurement_name=None,
        patches=[signal_patch_json],
        modifier_settings={
            'normsys': {'interpcode': 'code4'},
            'histosys': {'interpcode': 'code4p'},
        },
    )
    result = pyhf.infer.hypotest(
        1.0, workspace.data(model), model, qtilde=True, return_expected_set=True
    )
    return result[0].tolist()[0], result[-1].ravel().tolist()