     place_bombs(pid, [coord])
   end
 
+  @doc """
+  Places a bomb on each of the board squares at the given coordinates.
+
+  Returns `:ok` on success, or `{:error, :invalid_coord}` on failure.
+  """
   @spec place_bombs(pid, [coord]) :: :ok | {:error, :invalid_coord}
   def place_bombs(pid, coords) do
     parsed_coords = coords |> Enum.map(&parse_coord(pid, &1))


    char - ?a + 1
  end

  # Reveal all the squares on a `board` for debugging.
  @doc false

    end)
  end

  @doc """
  Places a bomb on `count` number of randomly selected board squares.
  """
  @spec place_random_bombs(pid, pos_integer) :: :ok
  def place_random_bombs(pid, count \\ @bomb_count) do
    board = get(pid)
