input: Write a python function to generate a Fibonacci series up to a given number of elements.
  assert fibonacci_series(5) == [0, 1, 1, 2, 3]
  assert fibonacci_series(10) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
  assert fibonacci_series(0) == []
  assert fibonacci_series(1) == [0]
output: def fibonacci_series(n):
      if n == 0:
          return []
      elif n == 1:
          return [0]
      
      fib_series = [0, 1]
      for i in range(2, n):
          fib_series.append(fib_series[-1] + fib_series[-2])
      
      return fib_series