The array class has various methods of removing elements from the array.

Let's look at the array

 arr = [5, 6, 5, 4, 3, 1, 2, 5, 4, 3, 3, 3] 

• Delete an element from the end of the array

 > arr.pop
 => 3

• Delete an element from the beginning of the array

 > arr.shift
 => 5

• Delete an element at a given position

 > arr.delete_at(2)
 => 4

• Delete all occurrences of a given element

 > arr.delete(5)
 => 5
 > arr
 => [6, 3, 1, 2, 4, 3, 3]

Your task is to complete the functions below using syntax as explained above.