message: [terminal] Sequence: Adds helper leaderSymbol() accessor.
diff: @@ -300,6 +300,7 @@ class Sequence
  {
  return intermediateCharacters_;
  }
  + [[nodiscard]] char leaderSymbol() const noexcept { return leaderSymbol_; }
  [[nodiscard]] char finalChar() const noexcept { return finalChar_; }
  template <typename T = unsigned>
  