input: Write a function to print the Fibonacci series up to n numbers where n is a user input.
  assert fibonacci(10)==0 1 1 2 3 5 8 13 21 34
  assert fibonacci(5)==0 1 1 2 3
  assert fibonacci(1)==0
  assert fibonacci(2)==0 1
  assert fibonacci(0)=="No Fibonacci series when n is 0"
output: def fibonacci(n):
      if n == 0:
          return "No Fibonacci series when n is 0"
      elif n == 1:
          return "0"
      elif n == 2:
          return "0 1"
      else:
          fib_series = [0, 1]
          for i in range(2, n):
              fib_series.append(fib_series[-1] + fib_series[-2])
          return ' '.join(map(str, fib_series))