input: Write a function to remove all occurrences of a given element from a given array. If the given array is empty, return the array as is.
  
  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([10, 10, 10, 10], 10)==[]
  assert remove_element([], 2)==[]
  assert remove_element([7, 7, 7], 8)==[7, 7, 7]
output: def remove_element(arr, elem):
      return [x for x in arr if x != elem]