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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_viable_phone_number(number):
 """Checks to see if a string could possibly be a phone number. At the moment, checks to see that the string begins with at least 2 digits, ignoring any punctuation commonly found in phone numbers. This method does not require the number to be normalized in advance - but does assume that leading non-number symbols have been removed, such as by the method _extract_possible_number. Arguments: number -- string to be checked for viability as a phone number Returns True if the number could be a phone number of some sort, otherwise False """

    if len(number) < _MIN_LENGTH_FOR_NSN:
        return False
    match = fullmatch(_VALID_PHONE_NUMBER_PATTERN, number)
    return bool(match)