class_docstr: A blocking operator that executes once its inputs are complete.
  
  This operator implements distributed sort / shuffle operations, etc.
code: def _add_input_inner(self, refs: RefBundle, input_index: int) -> None:
      assert not self.completed()
      assert input_index == 0, input_index
      self._input_buffer.append(refs)
  
imports: from typing import List, Optional
  from ray.data._internal.execution.interfaces import AllToAllTransformFn, PhysicalOperator, RefBundle, TaskContext
  from ray.data._internal.logical.interfaces import LogicalOperator
  from ray.data._internal.progress_bar import ProgressBar
  from ray.data._internal.stats import StatsDict
label_desc: Use image node_id 3 for calling the AllToAllOperator obj's underlying member method code with example usage: obj._add_input_inner(refs, input_index) without return types