code: def getIndexedLength(self) :
  		
  		if self.x1 != None and self.x2 != None:
  			return self.x2 - self.x1
  		else :
  			if len(self.children) == 0 :
  				return 0
  			else :
  				l = self.children[0].x2 - self.children[0].x1
  				for i in range(1, len(self.children)) :
  					l += self.children[i].x2 - self.children[i].x1 - max(0, self.children[i-1].x2 - self.children[i].x1)
  				return l
docs: Returns the total length of indexed regions