/**

  * simplifies the token stream to ease the matching with the expected token stream.

  * Simplifies the token stream to ease the matching with the expected token stream.
  *
  * * Strings are kept as-is
  * * in arrays each value is transformed individually
  * * Values that are empty (empty arrays or strings only containing whitespace)
  *
  * @param {TokenStream} tokenStream Description
  * @returns {SimplifiedTokenStream} description
  */
