Write a function, called mixed$\_$string, that takes a word string and computes a

list of

# all words generated by a single swap of letters in the word.

# For example $$swap$$ should return $[\text{'}$pwas$\text{'},$ 'wsap', 'sawp', 'swpa'$]($notice that

letters are

# only swapped with their immediate neighbors only, i$.$e$.$ you don$$t have $$waps$)$

# $(10$ points$)$