Lastly, you'll need to look up values in the environment.
;; CONTRACT
;; lookup-in-env : env id -> value
You should take your environment (a list of env-pairs) and an id structure, and find the env-pair that contains the same symbol as the id structure. Your function should then return the value.
Note that this is a very simple recursive function that will follow the template that you became familiar with in our last assignment. You are given a list of structures (implying you need to look inside of them for information) and an identifier (that is also a structure), but other than that, it's just a simple list processing function.
