public boolean isOperator(String token) {
		if (token.length() == 1) {	// Accounting for symbols such as +,-,*,/,%
			if (operators.containsValue(token.charAt(0))) {
				return true;
			}
		}
		if (operators.containsKey(token.toLowerCase())) {
			return true;
		} else {
			return false;
		}
	}