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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 _raw_input_contains_national_prefix(raw_input, national_prefix, region_code):
 """Check if raw_input, which is assumed to be in the national format, has a national prefix. The national prefix is assumed to be in digits-only form."""

    nnn = normalize_digits_only(raw_input)
    if nnn.startswith(national_prefix):
        try:
            # Some Japanese numbers (e.g. 00777123) might be mistaken to
            # contain the national prefix when written without it
            # (e.g. 0777123) if we just do prefix matching. To tackle that, we
            # check the validity of the number if the assumed national prefix
            # is removed (777123 won't be valid in Japan).
            return is_valid_number(parse(nnn[len(national_prefix):], region_code))
        except NumberParseException:
            return False
    return False