code: def _flatten(nested: InT) -> InnerInT:
      flat: List = []
      for item in nested:
          flat.extend(item)
      return cast(InT, flat)
  
imports: from typing import Any, Callable, List, Optional, Sequence, Tuple, TypeVar, cast
  from ..config import registry
  from ..model import Model
  from ..types import ArrayXd, ListXd
label_desc: Use image node_id 3 for calling a global function with example usage: _flatten(nested) and returns: cast