function saveLastChar(char) {
      const nextPos = (twoLastCharsPos + 1) % 2;
      const ret =
        twoLastChars[twoLastCharsPos] !== " " && twoLastChars[nextPos] === " ";
      twoLastChars[twoLastCharsPos] = char;
      twoLastCharsPos = nextPos;

      return !keepWhiteSpace && ret;
    }
Save the last char.
@param {string} char
@returns {boolean} true when the two last chars before adding the new one
are a non-whitespace followed by a whitespace.