code: function op2(value, priority) {
  	if (value === MULTIPLY) {
  		priority += 1;
  	} else if (value === DIVIDE || value === INT_DIVIDE) {
  		priority += 2;
  	}
  
  	return new Token(OP2, value, priority);
  }
docs: Binary operator factory
  @param  {Number} value    Operator  character code
  @param  {Number} priority Operator execution priority
  @return {Token[]}