input: Write a python function to create a symmetric matrix from a list.
  assert create_symmetric_matrix([1, 2, 3]) == [[1, 2, 3], [2, 2, 3], [3, 3, 3]]
  assert create_symmetric_matrix([4, 5, 6]) == [[4, 5, 6], [5, 5, 6], [6, 6, 6]]
  assert create_symmetric_matrix([7, 8, 9, 10]) == [[7, 8, 9, 10], [8, 8, 9, 10], [9, 9, 9, 10], [10, 10, 10, 10]]
output: def create_symmetric_matrix(lst):
      return [[max(lst[i], lst[j]) for j in range(len(lst))] for i in range(len(lst))]