def METHOD_NAME():
    usys1 = UnitSystem([u.kpc, u.Gyr, u.Msun, u.radian])
    usys2 = UnitSystem([u.pc, u.Myr, u.Msun, u.degree])
    p = MyPotential(m=1.E10*u.Msun, x0=0., units=usys1)
    assert p.parameters['m'].unit == usys1['mass']
    p2 = p.replace_units(usys2)
    assert p2.parameters['m'].unit == usys2['mass']
    assert p.units == usys1
    assert p2.units == usys2