$"$## Question $6$: first$\_$duplicate function $(8$ marks$)$

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"Write a function called first$\_$duplicate that takes a list as an argument and returns the first element that is duplicated in the list. If no duplicates are found, the function should return None. Hint: One way of doing this is to use the count method to see how many instances of each element there are. If there is more than $1,$ it means that that element is duplicated.

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"Write code to test the function first$\_$duplicate with a list of numbers and a list of tuples. If your function does not work with both types, then change it until it does work with these two types."

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