code: def _r2s(
      tensor: torch.Tensor,
      old_dist_spec: _DistSpec,
      dist_spec: _DistSpec,
      pg: ProcessGroup,
  ) -> torch.Tensor:
      DistSpecManager._sanity_check(old_dist_spec, dist_spec)
      return DistSpecManager._shard_as(
          tensor, old_dist_spec, dist_spec, pg
      )
  
imports: from contextlib import contextmanager
  import torch
  import torch.distributed
  from numpy import prod
  from colossalai.legacy.tensor.distspec import DistPlacementPattern, _DistSpec
  from colossalai.legacy.tensor.process_group import ProcessGroup
label_desc: Use image node_id 6 for calling the DistSpecManager obj's underlying member method code with example usage: obj._r2s(tensor, old_dist_spec, dist_spec, pg) and returns: DistSpecManager