code: private RValue[] executeExpressions(Tuple<Expr> expressions, CallStack frame) {
  		RValue[][] results = new RValue[expressions.size()][];
  		int count = 0;
  		for(int i=0;i!=expressions.size();++i) {
  			results[i] = executeMultiReturnExpression(expressions.get(i),frame);
  			count += results[i].length;
  		}
  		RValue[] rs = new RValue[count];
  		int j = 0;
  		for(int i=0;i!=expressions.size();++i) {
  			Object[] r = results[i];
  			System.arraycopy(r, 0, rs, j, r.length);
  			j += r.length;
  		}
  		return rs;
  	}
docs: Execute one or more expressions. This is slightly more complex than for
  the single expression case because of the potential to encounter
  "positional operands". That is, severals which arise from executing the
  same expression.
  
  @param expressions
  @param frame
  @return