input: 
  Write a function to generate and print the Fibonacci series up to the nth number where n is provided as an input. If n is less than or equal to 0, print an appropriate message.
  assert fibonacci_series(10) == None
  # Output: Fibonacci Series: 0 1 1 2 3 5 8 13 21 34
  assert fibonacci_series(5) == None
  # Output: Fibonacci Series: 0 1 1 2 3
  assert fibonacci_series(-1) == None
  # Output: Please enter a positive integer
  assert fibonacci_series(0) == None
  # Output: Please enter a positive integer
  
output:     
      if n <= 0:
          print("Please enter a positive integer")
          return
      
      a, b = 0, 1
      series = []
      for _ in range(n):
          series.append(a)
          a, b = b, a + b
      
      print("Fibonacci Series:", ' '.join(map(str, series)))
  