input: Write a function to remove all occurrences of the given element in a given array. If the given array is empty then return an empty array.
  assert remove_element([2, 4, 5, 7, 4, 2], 4) == [2, 5, 7, 2]
  assert remove_element([1, 2, 3, 4, 5], 6) == [1, 2, 3, 4, 5]
  assert remove_element([], 4) == []
  assert remove_element([1, 7, 7, 7, 1], 7) == [1, 1]
  assert remove_element([3, 3, 3, 3], 3) == []
output: def remove_element(arr, elem):
      return [x for x in arr if x != elem]