input: Write a python function to iterate through the first 20 characters of a given string and print them. If an exception occurs, print the exception.
  assert your_function("abcdefghij"*3) == None # It should print 'a' to 't'
  assert your_function("") == None # It should print an exception since the string is empty
  assert your_function("1234567890") == None # It should print '1' to '0'
output: def your_function(s):
      try:
          for i in range(20):
              print(s[i])
      except Exception as e:
          print(e)