code: def find(self, chrom, start, end):
          
  
          tree = self._trees.get( chrom, None )
          if tree:
              return tree.find( start, end )
          #return always a list
          return []
docs: find the intersecting elements
  
          :param chrom: chromosome
          :param start: start
          :param end: end
          :return: a list of intersecting elements