TASK DEFINITION: In this task you will be given a list of numbers and you should remove all duplicates in the list. If every number is repeated in the list an empty list should be returned. Your list should be numbers inside brackets, just like the given list.
PROBLEM: [4, 1, 6, 4, 7, 5, 4]

SOLUTION: [1, 6, 7, 5]

PROBLEM: [5, 1, 5, 4, 7, 2, 7, 4, 1, 5]

SOLUTION: [2]

PROBLEM: [4, 4, 4, 1, 3, 7]

SOLUTION:
[1, 3, 7]