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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 get_beam(secret_uuid):
 """ Get a beam from the session with `secret_uuid`. Parameters secret_uuid : str Returns ------- The beam object if it exists, otherwise `None`. """

    beam_dir = get_beam_cache_directory()
    beam_filename = os.path.join(beam_dir, secret_uuid)
    if os.path.isfile(beam_filename):
        with open(beam_filename, 'rb') as handle:
            beam = pickle.load(handle)
        return beam
    else:
        return None