code: def __call__(self, length):
      def _call():
          start = 0
          end = self.initial_length
          while end <= length:
              yield _Pair(start, end)
              start += self.start_step
              end += self.end_step
  
      windows = list(_call())
      if len(windows) == 0:
          raise ValueError(
              f"Length {length} too short for given window parameters."
          )
      return [windows]
  
imports: import collections
  import numpy
label_desc: Use image node_id 2 for calling the _ExpandingSliding obj's underlying member method code with example usage: obj.__call__(length) and returns: list