input: 
  def exponential_series(x: float, n: int) -> float:
      """Calculates the sum of an exponential series from 0 to n for a given base x.
      >>> exponential_series(2, 3)
      15
      >>> exponential_series(3, 2)
      13
      """
      sum = 0
      for i in range(n+1):
          sum += x ** i
      return sum
  
output:     sum = 0
      for i in range(n+1):
          sum += x ** i
      return sum