How to generate k+1 length strings from a list of k length strings?

[MTD]

Try this:

def k2k1(string1, string2):
    for c in string1:
        string2 = string2.replace(c,"",1)

    if len(string2) == 1:
        string1 += string2

    return string1    

print k2k1("abcd", "ebcd")