public Truss popSpan(){
  Span span=stack.removeLast();
  builder.setSpan(span.span,span.start,builder.length(),SPAN_INCLUSIVE_EXCLUSIVE);
  return this;
}

public Truss popSpan ( ) { Span span = stack . removeLast ( ) ; builder . setSpan ( span . span , span . start , builder . length ( ) , SPAN_INCLUSIVE_EXCLUSIVE ) ; return this ; }
end the most recently pushed span at the current position in the builder .
