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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 _FixedSizer(value_size):
 """Like _SimpleSizer except for a fixed-size field. The input is the size of one value."""


  def SpecificSizer(field_number, is_repeated, is_packed):
    tag_size = _TagSize(field_number)
    if is_packed:
      local_VarintSize = _VarintSize
      def PackedFieldSize(value):
        result = len(value) * value_size
        return result + local_VarintSize(result) + tag_size
      return PackedFieldSize
    elif is_repeated:
      element_size = value_size + tag_size
      def RepeatedFieldSize(value):
        return len(value) * element_size
      return RepeatedFieldSize
    else:
      field_size = value_size + tag_size
      def FieldSize(value):
        return field_size
      return FieldSize

  return SpecificSizer