input: Write a function to search a number in an array.
  assert search_in_array([1, 5, 8, 9], 5) == True
  assert search_in_array([1, 5, 8, 9], 7) == False
  assert search_in_array([2, 4, 6, 8, 10], 6) == True
  assert search_in_array([2, 4, 6, 8, 10], 3) == False
output: def search_in_array(arr, num):
      return num in arr