text: from __future__ import division
  from cctbx_xray_observations_ext import *
  
  def customized_copy(obs, twin_fractions=None, twin_components=None):
    """ Creates a copy of the observation object and with new twin fractions
    and twin components
    """
    twf = ()
    if twin_fractions is not None:
      twf = twin_fractions
    twc = ()
    if twin_components is not None:
      twc = twin_components
    result = observations(obs, twf, twc)
    result.fo_sq = obs.fo_sq
    result.ref_twin_fractions = twin_fractions
    result.ref_twin_components = twin_components
    return result
  