bool inputStart = true;
  bool wordStart = true;
  for (const char c : str) {
    // Find a word start.
    if (c == delimiter) {
      // Repeated cases of wordStart means explicit delimiter usage.
      if (wordStart) {
        result.push_back(delimiter);
      }
      wordStart = true;
      continue;
    }
    if (!from_snake && isupper(c)) {
      wordStart = true;
    }

    // add delimiter