code: def _call(self, f, out):
          
          if self.exponent == 1.0:
              self._call_vecfield_1(f, out)
          elif self.exponent == float('inf'):
              self._call_vecfield_inf(f, out)
          else:
              self._call_vecfield_p(f, out)
docs: Implement ``self(f, out)``.