input: Write a function to print the following pattern: for each row i (1 to 5), print the numbers from 1 to i, each number separated by a space. Each row should end with a newline character.
  for i in range(1,6):
      for j in range(1,i+1):
          print(j, end=" ")
      print()
  assert pattern_output()==None
output: def pattern_output():
      for i in range(1, 6):
          for j in range(1, i + 1):
              print(j, end=" ")
          print()