More-foul-logical sounds

Consider the allomorphs of the plural morpheme in English: [z] (as in dogs), [s] (as in cats), [z] (as in foxes). Let's represent them with the arpabet symbols Z, S and IH Z.

Create an FST that takes as input the pronunciation of a noun (represented using arpabet symbols as in the CMU pronunciation dictionary) concatenated with a representation of the plural morpheme and the end of word symbol # used by J&M, and outputs the pronunciation of the plural form of the noun, followed by the symbol #.

For example, given the input:

d aa g ^ s #

(which corresponds to the word dog, the arbitrary symbol ^, the plural morpheme s, and the end of word symbol #) will produce as output

d aa g z #

(which is the pronunciation of the plural form dogs).

Other examples:

Input (cat+s)

k ae t ^ s #

Output (cats)

k ae t s #

Input (flash+s)

f l ae sh ^ s #

Output (flashes)

f l ae sh ih z #