code: def forward(self, sample: str):
      sample = self.serve_input._call_load_sample(sample)
      if not isinstance(sample, list):
          sample = [sample]
      return self.collate_fn(sample)
  
file_path: lightning-flash/src/flash/core/data/batch.py
imports: from typing import TYPE_CHECKING, Any, Callable, List
  from torch import Tensor, nn
  from flash.core.data.utilities.classification import _is_list_like
label_desc: Use image node_id 2 for calling the _ServeInputProcessor obj's underlying member method code with example usage: obj.forward(sample) and returns: self