input: Write a python function to print a right-angled triangle pattern with numbers increasing in each row.
  assert print_triangle(3) == "1\n12\n123\n"
  assert print_triangle(5) == "1\n12\n123\n1234\n12345\n"
  assert print_triangle(1) == "1\n"
output: def print_triangle(n):
      result = []
      for i in range(1, n + 1):
          result.append(''.join(str(x) for x in range(1, i + 1)))
      return '\n'.join(result) + '\n'