def METHOD_NAME():
    from iminuit import Minuit
    def fcn(x, y, z):
        return (x - 1) ** 2 + (y - 4) ** 2 / 2 + (z - 9) ** 2 / 3
    m = Minuit(fcn, x=0.0, y=0.0, z=0.0)
    m.migrad()
    m.fixed["x"] = True
    m.errors["x"] = 2
    m.hesse()  # this used to release x
    assert m.fixed["x"]
    assert m.errors["x"] == 2