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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find(self, chrom, start, end):
 """find the intersecting elements :param chrom: chromosome :param start: start :param end: end :return: a list of intersecting elements"""


        tree = self._trees.get( chrom, None )
        if tree:
            return tree.find( start, end )
        #return always a list
        return []