input: Write a function to design a positive feedback loop for the given Python program. The function should modify the input loop so that after printing "hello" the specified number of times, it prints "You've got it!" if the loop completes successfully. If the input loop is empty or invalid, the function should return the original loop without any changes.
  assert positive_feedback_loop('for i in range(10):\\n    print("hello")')=='for i in range(10):\\n    print("hello")\\n    i += 1\\n    if i == 10:\\n        print("You've got it!")'
  assert positive_feedback_loop('for i in range(5):\\n    print("hi")')=='for i in range(5):\\n    print("hi")\\n    i += 1\\n    if i == 5:\\n        print("You've got it!")'
  assert positive_feedback_loop('')==''
  assert positive_feedback_loop('for i in range(3):\\n    print("greetings")')=='for i in range(3):\\n    print("greetings")\\n    i += 1\\n    if i == 3:\\n        print("You've got it!")'
output: def positive_feedback_loop(loop):
      if not loop or 'for' not in loop or 'in range' not in loop:
          return loop
      lines = loop.split('\n')
      for_line = lines[0]
      range_value = for_line.split('range(')[1].split(')')[0]
      modified_loop = f"{loop}\n    i += 1\n    if i == {range_value}:\n        print(\"You've got it!\")"
      return modified_loop