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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 _add_not_exposed( analysis_row, enable_rounding, is_population, exposure_unit, coefficient):
 """Helper to add the `not exposed` item to the legend. :param analysis_row: The analysis row as a list. :type analysis_row: list :param enable_rounding: If we need to do a rounding. :type enable_rounding: bool :param is_population: Flag if the number is population. It needs to be used with enable_rounding. :type is_population: bool :param exposure_unit: The exposure unit. :type exposure_unit: safe.definitions.units :param coefficient: Divide the result after the rounding. :type coefficient:float :return: A tuple with the color and the formatted label. :rtype: tuple """

    # We add the not exposed class at the end.
    not_exposed_field = (
        hazard_count_field['field_name'] % not_exposed_class['key'])
    try:
        value = analysis_row[not_exposed_field]
    except KeyError:
        # The field might not exist if there is not feature not exposed.
        value = 0
    value = format_number(value, enable_rounding, is_population, coefficient)
    label = _format_label(
        hazard_class=not_exposed_class['name'],
        value=value,
        exposure_unit=exposure_unit)

    return not_exposed_class['color'], label