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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 unpack(tokens):
 """Evaluate and unpack the given computation graph."""

    logger.log_tag("unpack", tokens)
    if use_computation_graph:
        tokens = evaluate_tokens(tokens)
    if isinstance(tokens, ParseResults) and len(tokens) == 1:
        tokens = tokens[0]
    return tokens