def merge_the_tools(string, k):
    """
    This is a simple solution of O(N) time complexity
    
    First, we start iterating through the string at step k, this goes through each substring
    
    define each substring using string splicing
    
    using the fromkeys method which is a class method in pythons dict type. Creates a new dictionary from a sequence of keys or in this case chars, this assigns None to each key, and also removes duplicates, but still keeps the order. The alternative would have been to use some sort of set casting but I've come to find that that doesn't preserve order. 
    
    Then we use the string method 'join' with an empty string as the delimiter (aka the string for which the method is called upon) to get our u
    """
    
    for i in range(0, len(string), k):
        substr = string[i: i+k]
        shaved = "".join(dict.fromkeys(substr))   
        print(shaved)