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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 parse_version(output):
 """ Parses the supplied output and returns the version string. :param output: A string containing the output of running snort. :returns: Version string for the version of snort run. None if not found. """

    for x in output.splitlines():
        match = VERSION_PATTERN.match(x)
        if match:
            return match.group('version').strip()
    return None