code: public void invokeOperator(PdfLiteral operator, ArrayList operands) {
  		ContentOperator op = operators.get(operator.toString());
  		if (op == null) {
  			// skipping unssupported operator
  			return;
  		}
  		op.invoke(this, operator, operands);
  	}
docs: Invokes an operator.
  @param operator	the PDF Syntax of the operator
  @param operands	a list with operands