code: def toposort(dsk, dependencies=None):
      """Return a list of keys of task graph sorted in topological order."""
      return _toposort(dsk, dependencies=dependencies)
  
imports: from collections import defaultdict
  from typing import List, Sequence
  from flash.core.utilities.imports import _TOPIC_SERVE_AVAILABLE
label_desc: Use image node_id 13 for calling a global function with example usage: toposort(dsk, dependencies) and returns: _toposort