docs: def _set_initial_wcxf(self, wc, get_smpar=True):
          """Load the initial values for Wilson coefficients from a
          wcxf.WC instance.
  
          Parameters:
  
          - `get_smpar`: boolean, optional, defaults to True. If True, an attempt
            is made to determine the SM parameters from the requirement of
            reproducing the correct SM masses and mixings at the electroweak
            scale. As approximations are involved, the result might or might not
            be reliable, depending on the size of the Wilson coefficients
            affecting the SM masses and mixings. If False, Standard Model
            parameters have to be provided separately and are assumed to be in
            the weak basis used for the Warsaw basis as defined in WCxf,
            i.e. in the basis where the down-type and charged lepton mass
            matrices are diagonal.
          """
          if wc.eft != 'SMEFT':
              raise ValueError("Wilson coefficients use wrong EFT.")
          if wc.basis != 'Warsaw':
              raise ValueError("Wilson coefficients use wrong basis.")
          self.scale_in = wc.scale
          C = wilson.util.smeftutil.wcxf2arrays_symmetrized(wc.dict)
          # fill in zeros for missing WCs
          for k, s in smeftutil.C_keys_shape.items():
              if k not in C and k not in smeftutil.SM_keys:
                  if s == 1:
                      C[k] = 0
                  else:
                      C[k] = np.zeros(s)
          if self.C_in is None:
              self.C_in = C
          else:
              self.C_in.update(C)
          if get_smpar:
              self.C_in.update(self._get_sm_scale_in())