docs: def find_index(array, x):
      """
      Locate the leftmost value exactly equal to x.
  
      :type array: list
      :param array: an iterable object that support inex
  
      :param x: a comparable value
  
      **中文文档**
  
      返回第一个值等于x的元素的索引。
      """
      i = bisect.bisect_left(array, x)
      if i != len(array) and array[i] == x:
          return i
      raise ValueError