code: def dump_wcxf(self, C_out, scale_out, fmt='yaml', stream=None, **kwargs):
          
          wc = self.get_wcxf(C_out, scale_out)
          return wc.dump(fmt=fmt, stream=stream, **kwargs)
docs: Return a string representation of the Wilson coefficients `C_out`
          in WCxf format. If `stream` is specified, export it to a file.
          `fmt` defaults to `yaml`, but can also be `json`.
  
          Note that the Wilson coefficients are rotated into the Warsaw basis
          as defined in WCxf, i.e. to the basis where the down-type and charged
          lepton mass matrices are diagonal.