has_duplicates()

Returns True if there are duplicate values in a flast list, False otherwise.

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

def has_duplicates(lst):
  return len(lst) != len(set(lst))

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