'Update the parameters of the model
Parameters
params : array_like
Array of new parameters.
transformed : boolean, optional
Whether or not `params` is already transformed. If set to False,
`transform_params` is called. Default is True.
Returns
params : array_like
Array of parameters.
Notes
Since Model is a base class, this method should be overridden by
subclasses to perform actual updating steps.'

def update(self, params, transformed=True, complex_step=False):

    params = np.array(params, ndmin=1)
    if (not transformed):
        params = self.transform_params(params)
    return params
