def METHOD_NAME(self, start, end):
   # short circuit if not within the bound
   if (end < self.start or start > self.end):
       return 0 
   sbound = self.start if start < self.start else start
   ebound = self.end if end > self.end else end
   ratio = float(ebound-sbound) / (end-start) 
   return self.value*ratio/ctx.divisor