input: Write a function to print the Fibonacci series up to a given number. If the input number is less than 0, the function should print "Incorrect input". The function should return the last Fibonacci number when the input number is greater than or equal to 0.
  def fibonacci_series(n):
      if n < 0:
          print("Incorrect input")
          return
      a, b = 0, 1
      print(a, end=" ")
      if n > 0:
          print(b, end=" ")
      for i in range(1, n):
          c = a + b
          a = b
          b = c
          print(b, end=" ")
  
  assert fibonacci_series(5)==None
  assert fibonacci_series(-1)==None
  assert fibonacci_series(0)==None
  assert fibonacci_series(1)==None
  assert fibonacci_series(10)==None
output: def fibonacci_series(n):
      if n < 0:
          print("Incorrect input")
          return
      a, b = 0, 1
      if n == 0:
          return a
      for i in range(1, n):
          c = a + b
          a = b
          b = c
      return b