def string_scramble(word1, word2):
    """
    craeted empty list and u/case letters
    (if any) in words converted to l/case
    """
    x = []
    word1 = word1.lower()
    word2 = word2.lower()
    """
    each letter in word1 iterates thru word2 and
    appends letter unrepeated to x if found
    common
    """
    for i in range(len(word1)):
        for j in range(len(word2)):
            if word1[i] not in x:
                if word1[i] == word2[j]:
                    x.append(word1[i])
    return x

print(string_scramble('GraSS', 'grilled cheese'))
print(string_scramble('Newark', 'New York'))
print(string_scramble('Barbeque', 'Cheese Burger'))
print(string_scramble('East Coast', 'New York'))
print(string_scramble('GraSS', 'cheese'))
print(string_scramble('Einstein', 'Newton'))