     zone_group_lines = Enum.slice lines, 2..4
 
     Stream.zip(zone_group_lines)
+      |> Stream.drop(1)
       |> Stream.map(&Tuple.to_list/1)
       |> Stream.map(fn(zone_group_parts) -> Enum.join(zone_group_parts, " ") end)
       |> Enum.map(&String.trim/1)

  up two lines

      iex> Mix.Tasks.Parcel.IngestLandUseTable.get_zone_groups([
      ...>   ["Ignore", "these"],
      ...>   ["two", "rows"],
      ...>   ["M", ""],
      ...>   ["H", "O"],
      ...>   ["P", "N"]
      ...> ])
      ["M H P", "O N"]
  """

      ...> "O N"  # real
      ...> ])
      ["GO", "PREDS"]
  """
  def get_unmapped_zone_groups(zone_groups) do
    actualy_zone_groups = zone_groups

    actualy_zone_groups -- Map.keys(@zone_groups_to_zone_codes)
  end
