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Inverse functions
Inverse functions are a rather fascinating class of functions in that if we have two functions and we apply them on each other, we receive the identity. Mathematically, we define this as follows:
Suppose we have 
. Then, they are only inverse functions if 
. For example, we could have 
and 
. Therefore, 
, which tells us that 
.
Here is another cool property that this has:
