private static String[][] unifyVariable(String variable, String sentence, String[][] currentSub){
		for(int i = 1; i < currentSub.length; i++){
			if(currentSub[i][0] != null){
				if(currentSub[i][0].equals(variable)){
					return currentSub;
				}
				else if(currentSub[i][0].equals(sentence)){
					return currentSub;
				}
			}
		}
		if(occursCheck(variable, sentence)){
			currentSub[0][0] = "failure";
			return currentSub;
		}
		else{
			for(int i = 1; i < currentSub.length; i++){
				if(currentSub[i][0] == null || currentSub[i][0].equals("")){
					if(isVariable(variable)){
						currentSub[i][0] = variable;
						currentSub[i][1] = sentence;
					}
					else{
						currentSub[i][1] = variable;
						currentSub[i][0] = sentence;
					}
					i = currentSub.length;
				}
			}
		}
		return currentSub;
	}