input: def print_pattern() -> None:
      """Prints a pattern where each line contains numbers from 1 to the line number.
      >>> print_pattern()
      1
      12
      123
      1234
      12345
      """
      for i in range(1, 6):
          for j in range(1, i + 1):
              print(j, end="")
          print()
output:     for i in range(1, 6):
          for j in range(1, i + 1):
              print(j, end="")
          print()