input: Write a python function to merge two arrays and print the result.
  assert merge_arrays([1, 2, 6, 9, 11], [2, 3, 4, 7, 8]) == [1, 2, 6, 9, 11, 2, 3, 4, 7, 8]
  assert merge_arrays([10, 20], [30, 40]) == [10, 20, 30, 40]
  assert merge_arrays([], [1, 2, 3]) == [1, 2, 3]
output: def merge_arrays(arr1, arr2):
      return arr1 + arr2