code: @Override
    public String escape(String string) {
      checkNotNull(string); // GWT specific check (do not optimize)
      // Inlineable fast-path loop which hands off to escapeSlow() only if needed
      int length = string.length();
      for (int index = 0; index < length; index++) {
        if (escape(string.charAt(index)) != null) {
          return escapeSlow(string, index);
        }
      }
      return string;
    }
docs: Returns the escaped form of a given literal string.
  
  @param string the literal string to be escaped
  @return the escaped form of {@code string}
  @throws NullPointerException if {@code string} is null