public static void classify(LinkedList<Token> tokens) {
		// There are two types of arithmetic expression: unary (+,- only) and binary (+,- =,*,/,%).
		// From the order of the oper LinkedList, classify the operators
		Token.TokenType prev = Token.TokenType.UNARY;   // Start start is analagous to previous token being unary operator
		int length = tokens.size();
		for (int i = 0; i < length; i++) {
			Token tok = tokens.get(i);
			if (tok.isOperand()) {
				prev = Token.TokenType.OPERAND;
			} else if (tok.isOperator()) {
				if (prev == Token.TokenType.OPERAND) {		// If the previous token was an operand,
					tok.setBinary();		// then this operator is binary.
					prev = Token.TokenType.BINARY;
				} else if (prev == Token.TokenType.UNARY) {	// If the previous token was a unary operator,
					tok.setUnary();						// then this operator is unary
				} else if (prev == Token.TokenType.BINARY) {   	 // If the previous token was a binary operator,
					tok.setUnary(); 			  			 // then this operator is unary.
					prev = Token.TokenType.UNARY;
				}						
			} else {
				throw new RuntimeException("Token is neither operator nor operand.");
			}
		}
	}