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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 is_valid(hal_id):
 """ Check that a given HAL id is a valid one. :param hal_id: The HAL id to be checked. :returns: Boolean indicating whether the HAL id is valid or not. True True True False """

    match = REGEX.match(hal_id)
    return (match is not None) and (match.group(0) == hal_id)