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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_argv(tokens, options, options_first=False):
 """Parse command-line argument vector. If options_first: argv ::= [ long | shorts ]* [ argument ]* [ '--' [ argument ]* ] ; else: argv ::= [ long | shorts | argument ]* [ '--' [ argument ]* ] ; """

    parsed = []
    while tokens.current() is not None:
        if tokens.current() == '--':
            return parsed + [Argument(None, v) for v in tokens]
        elif tokens.current().startswith('--'):
            parsed += parse_long(tokens, options)
        elif tokens.current().startswith('-') and tokens.current() != '-':
            parsed += parse_shorts(tokens, options)
        elif options_first:
            return parsed + [Argument(None, v) for v in tokens]
        else:
            parsed.append(Argument(None, tokens.move()))
    return parsed