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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 _expected_reads(run_info_file):
 """Parse the number of expected reads from the RunInfo.xml file. """

    reads = []
    if os.path.exists(run_info_file):
        tree = ElementTree()
        tree.parse(run_info_file)
        read_elem = tree.find("Run/Reads")
        reads = read_elem.findall("Read")
    return len(reads)