code: def join(sep: Doc, docs: Sequence[Doc]) -> Doc:
      """Concatenates `docs`, separated by `sep`."""
      docs = list(docs)
      if len(docs) == 0:
          return nil()
      xs = [docs[0]]
      for doc in docs[1:]:
          xs.append(sep)
          xs.append(doc)
      return concat(xs)
  
imports: from __future__ import annotations
  import abc
  from collections.abc import Sequence
  import enum
  from functools import partial
  import sys
  from typing import NamedTuple
  from jax._src import config
label_desc: Use image node_id 14 for calling a global function with example usage: join(sep, docs) and returns: concat, nil