code: @SuppressWarnings("unchecked")
  	public <T extends Operator> T geInstance(Opcode opcode) {
  		Operator operator = this.operators.get(opcode);
  		if (operator == null) {
  			throw new TemplateException("Operator |%s| is not implemented.", opcode);
  		}
  		return (T) operator;
  	}
docs: Get operator instance for requested opcode.
  
  @param opcode requested operator opcode.
  @return operator instance.
  @throws TemplateException if operator is not implemented.