code: def _logpdf(self, **kwargs):
          
          if kwargs in self:
              return sum([self._lognorm[p] +
                          self._expnorm[p]*(kwargs[p]-self._mean[p])**2.
                          for p in self._params])
          else:
              return -numpy.inf
docs: Returns the log of the pdf at the given values. The keyword
          arguments must contain all of parameters in self's params. Unrecognized
          arguments are ignored.