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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 _get_national_number_groups_without_pattern(numobj):
 """Helper method to get the national-number part of a number, formatted without any national prefix, and return it as a set of digit blocks that would be formatted together following standard formatting rules."""

    # This will be in the format +CC-DG1-DG2-DGX;ext=EXT where DG1..DGX represents groups of
    # digits.
    rfc3966_format = format_number(numobj, PhoneNumberFormat.RFC3966)
    # We remove the extension part from the formatted string before splitting
    # it into different groups.
    end_index = rfc3966_format.find(U_SEMICOLON)
    if end_index < 0:
        end_index = len(rfc3966_format)

    # The country-code will have a '-' following it.
    start_index = rfc3966_format.find(U_DASH) + 1
    return rfc3966_format[start_index:end_index].split(U_DASH)