@type diff_line() :: %{
  number: pos_integer(),
  line: String.t(),
  kind: diff_line_kind()
}

@type diff_line_kind() :: :old | :new | :shared

@type occurrence() ::
  {:one, non_neg_integer(), [String.t()], [String.t()]}
  | {:other, non_neg_integer(), [String.t()], [String.t()]}
  | {:both, non_neg_integer(), [String.t()], [String.t()], [String.t()],
     [String.t()]}

@type tagged_line() :: %{kind: diff_line_kind(), line: String.t()}