def fit_FC(model, data):
    """ Convenience function to fit a flow curve
        Args:

        model: rheology model (e.g. HB_model)

        data: pandas DataFrame with column 'Shear rate' and 'Stress'

        Returns:

        lmfit.fitresult
    """
    return model.fit(data["Stress"], x=data["Shear rate"], weights=1 / data["Stress"])