code: def find_lt(array, x):
      
      i = bisect.bisect_left(array, x)
      if i:
          return array[i - 1]
      raise ValueError
docs: Find rightmost value less than x.
  
      :type array: list
      :param array: an iterable object that support inex
  
      :param x: a comparable value
  
      Example::
  
          >>> find_lt([0, 1, 2, 3], 2.5)
          2
  
      **中文文档**
  
      寻找最大的小于x的数。