input: Write a function to debug the given Python code so that the function f2(2) returns the correct output. Ensure f1(x) returns x + 1 and f2(x) returns f1(x) * f1(x). If the code is already correct, return the original code with a comment stating that it is correct.
  assert f2(2)==9
  assert f2(3)==16
  assert f2(0)==1
  assert f2(-1)==0
  assert f2(-2)==1
  def f1(x):
      return x + 1
  
  def f2(x):
      return f1(x) * f1(x)
  
  print(f2(2)) #Output: 9
output: def f1(x):
      return x + 1
  
  def f2(x):
      return f1(x) * f1(x)