'Returns a copy of the object.'

def copy(self):

    obj = MixedLMParams(self.k_fe, self.k_re, self.k_vc)
    obj.fe_params = self.fe_params.copy()
    obj.cov_re = self.cov_re.copy()
    obj.vcomp = self.vcomp.copy()
    return obj
