all_unique()

Returns True if all the values in a list are unique, False otherwise.

Use set() on the given list to remove duplicates, use len() to compare its length with the length of the list.

def all_unique(lst):
  return len(lst) == len(set(lst))

x = [1, 2, 3, 4, 5, 6]
y = [1, 2, 2, 3, 4, 5]
all_unique(x) # True
all_unique(y) # False