code: def inverse_transform(self, maps):
          
          out = {}
          m1 = maps[parameters.mass1]
          m2 = maps[parameters.mass2]
          out[parameters.mchirp] = conversions.mchirp_from_mass1_mass2(m1, m2)
          out[parameters.q] = m1 / m2
          return self.format_output(maps, out)
docs: This function transforms from component masses to chirp mass and
          mass ratio.
  
          Parameters
          ----------
          maps : a mapping object
  
          Examples
          --------
          Convert a dict of numpy.array:
  
          >>> import numpy
          >>> from pycbc import transforms
          >>> t = transforms.MchirpQToMass1Mass2()
          >>> t.inverse_transform({'mass1': numpy.array([16.4]), 'mass2': numpy.array([8.2])})
              {'mass1': array([ 16.4]), 'mass2': array([ 8.2]),
               'mchirp': array([ 9.97717521]), 'q': 2.0}
  
          Returns
          -------
          out : dict
              A dict with key as parameter name and value as numpy.array or float
              of transformed values.