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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 tz_file(name):
 """ Open a timezone file from the zoneinfo subdir for reading. :param name: The name of the timezone. :type name: str :rtype: file """

    try:
        filepath = tz_path(name)

        return open(filepath, 'rb')
    except TimezoneNotFound:
        # http://bugs.launchpad.net/bugs/383171 - we avoid using this
        # unless absolutely necessary to help when a broken version of
        # pkg_resources is installed.
        try:
            from pkg_resources import resource_stream
        except ImportError:
            resource_stream = None

        if resource_stream is not None:
            try:
                return resource_stream(__name__, 'zoneinfo/' + name)
            except FileNotFoundError:
                return tz_path(name)

        raise