input: Write a function to print the Fibonacci series up to a given number. The function should return the series as a list. If the given number is less than 0, the function should return "Incorrect input".
  assert fibonacci(-1)== "Incorrect input"
  assert fibonacci(0)== [0]
  assert fibonacci(5)== [0, 1, 1, 2, 3]
  assert fibonacci(10)== [0, 1, 1, 2, 3, 5, 8]
output: def fibonacci(n):
      if n < 0:
          return "Incorrect input"
      if n == 0:
          return [0]
      fib_series = [0, 1]
      while fib_series[-1] + fib_series[-2] <= n:
          fib_series.append(fib_series[-1] + fib_series[-2])
      return fib_series