code: def _parse_Sigma(self,Sigma_amp,Sigma,dSigmadR,d2SigmadR2):
          
          if isinstance(Sigma,dict):
              Sigma= [Sigma]
          try:
              nsigma= len(Sigma)
          except TypeError:
              Sigma_amp= [Sigma_amp]
              Sigma= [Sigma]
              dSigmadR= [dSigmadR]
              d2SigmadR2= [d2SigmadR2]
              nsigma= 1
          self._nsigma= nsigma
          self._Sigma_amp= Sigma_amp
          self._Sigma= Sigma
          self._dSigmadR= dSigmadR
          self._d2SigmadR2= d2SigmadR2
          if isinstance(Sigma[0],dict):
              self._Sigma_dict= copy.copy(Sigma)
              self._parse_Sigma_dict()
          else:
              self._Sigma_dict= None
          return None
docs: NAME:
             _parse_Sigma
          PURPOSE:
             Parse the various input options for Sigma* functions
          HISTORY:
             2016-12-27 - Written - Bovy (UofT/CCA)