code: public CharSequence trim(CharSequence sequence) {
          return trim(sequence, TrimOption.BOTH, SpanCondition.SIMPLE);
      }
docs: Returns a trimmed sequence (using CharSequence.subsequence()), that omits matching elements at the start and
  end of the string, using TrimOption.BOTH and SpanCondition.SIMPLE. For example:
  
  <pre>
  {@code
  
  new UnicodeSet("[ab]").trim("abacatbab")}
  </pre>
  
  ... returns {@code "cat"}.
  @param sequence
  the sequence to trim
  @return a subsequence