old_contents: # -*- coding: utf-8 -*-
  
  __all__ = ["FibonacciGenerator"]
  
  
  class FibonacciGenerator(object):
      """
      """
  
      # We use List to cache already founded fibonacci numbers,
      # and 1 is the first fibonacci number.
      _fibonacci_list = [0, 1]  # 0 is placeholder
      skip_the_placeholder_idx = 1
  
      def generate(self, n):
          with_placehoder_len = n + 2
          while len(self._fibonacci_list) < with_placehoder_len:
              self._fibonacci_list.append(self.find_next_fibonacci())
  
          return self._fibonacci_list[self.skip_the_placeholder_idx:n+1]
  
      def find_next_fibonacci(self):
          """
          find the next fibonacci after the last number of `self._fibonacci_list`
          """
          assert len(self._fibonacci_list[-2:]) == 2, self._fibonacci_list[-2:]
          last2_num, last1_num = self._fibonacci_list[-2:]
          return last2_num + last1_num
  
new_contents: # -*- coding: utf-8 -*-
  
  __all__ = ["FibonacciGenerator"]
  
  
  class FibonacciGenerator(object):
      """
      """
  
      # We use List to cache already founded fibonacci numbers,
      # and 1 is the first fibonacci number.
      _fibonacci_list = [0, 1]  # 0 is placeholder
      skip_the_placeholder_idx = 1
  
      def generate(self, n):
          with_placehoder_len = n + 2
          while len(self._fibonacci_list) < with_placehoder_len:
              self._fibonacci_list.append(self.find_next_fibonacci())
  
          return self._fibonacci_list[self.skip_the_placeholder_idx: n + 1]
  
      def find_next_fibonacci(self):
          """
          find the next fibonacci after the last number of `self._fibonacci_list`
          """
          assert len(self._fibonacci_list[-2:]) == 2, self._fibonacci_list[-2:]
          last2_num, last1_num = self._fibonacci_list[-2:]
          return last2_num + last1_num
  
subject: Fix E226 missing whitespace around arithmetic operator