old_contents: // Check if two strings are isomorphic
  
  function isIsomorphic(stringOne, stringTwo) {
  	
  	// check if strings are of the same length
  	if (stringOne.length !== stringTwo.length) {
  		return false;
  	}
  
  }
  
new_contents: // Check if two strings are isomorphic
  
  function isIsomorphic(stringOne, stringTwo) {
  	
  	// check if strings are of the same length (if not, cannot be isomorphic)
  	if (stringOne.length !== stringTwo.length) {
  		return false;
  	}
  
  	var letterMap = {};
  
  	for (i = 0; i < stringOne.length; i++) {
  		var letterA = stringOne[i],
  			letterB = stringTwo[i];
  
  		// if the letter does not exist, create a map and map it to the value of the second letter
  		if (letterMap[letterA] === undefined) {
  			letterMap[letterA] = letterB;
  		}
  	}
  
  
  }
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
subject: Create loop and set first condition: if letter does not exist, create map and map it to value of second letter