## Function Description
Let `solve(prefix, s)` be a function that takes a prefix-string named
`prefix` and another string named `s`, finds all permutations of `s`
in alphabetical order, and prints each permutation prefixed by
`prefix`.
For example `solve("abc", "efd")` prints the following:
abcdef
abcdfe
abcedf
abcefd
abcfde
abcfed
As another example, note that `solve("abc", "ede")` prints the following:
abcdee
abcede
abceed