class_docstr: A blocking operator that executes once its inputs are complete.
  
  This operator implements distributed sort / shuffle operations, etc.
docstr: Initialize all internal sub progress bars, and return the number of bars.
docstr_tok: ["Initialize","all","internal","sub","progress","bars",",","and","return","the","number","of","bars","."]
code: def initialize_sub_progress_bars(self, position: int) -> int:
      """Initialize all internal sub progress bars, and return the number of bars."""
      if self._sub_progress_bar_names is not None:
          self._sub_progress_bar_dict = {}
          for name in self._sub_progress_bar_names:
              bar = ProgressBar(
                  name, self.num_outputs_total() or 1, position
              )
              # NOTE: call `set_description` to trigger the initial print of progress
              # bar on console.
              bar.set_description(f"  *- {name}")
              self._sub_progress_bar_dict[name] = bar
              position += 1
          return len(self._sub_progress_bar_dict)
      else:
          return 0
  
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 10 for calling the AllToAllOperator obj's underlying member method code with example usage: obj.initialize_sub_progress_bars(position) and returns: len, int