docs: def step( self ):
          """
          Returns the step value for this ruler.  If the cached value is None,
          then a default value will be specified based on the ruler type.
          
          :return     <variant>
          """
          if ( self._step is not None ):
              return self._step
          
          elif ( self.rulerType() == XChartRuler.Type.Number ):
              self._step = int((self.maximum() - self.minimum()) / 10.0)
          
          elif ( self.rulerType() == XChartRuler.Type.Date ):
              
              self._step = int(self.minimum().daysTo(self.maximum()) / 10.0) - 1
          
          elif ( self.rulerType() & (XChartRuler.Type.Time | \
                                     XChartRuler.Type.Datetime) ):
              self._step = int(self.minimum().secsTo(self.maximum()) / 10.0) - 1
          
          return self._step