def add_params(default_params, extra_params):
    """ Add params from extra_params to default_params

    Parameters
    ----------
    default_params : dict
        Original parameters
    extra_params : dict
        Extra parameters to add

    Returns
    ------
    params : dict
        Merged parameters, where extra_params can overwrite default_params

    """
    for k, v in extra_params.items():
        default_params[k] = v
    return default_params
