code: def walk(children, level=0, path=None, usename=True):
      """Generate all the full paths in a tree, as a dict.
  
      Examples
      --------
      >>> from nipype.pipeline.engine.utils import walk
      >>> iterables = [('a', lambda: [1, 2]), ('b', lambda: [3, 4])]
      >>> [val['a'] for val in walk(iterables)]
      [1, 1, 2, 2]
      >>> [val['b'] for val in walk(iterables)]
      [3, 4, 3, 4]
      """
      # Entry point
      if level == 0:
          path = {}
      # Exit condition
      if not children:
          yield path.copy()
          return
      # Tree recursion
      head, tail = children[0], children[1:]
      name, func = head
      for child in func():
          # We can use the arg name or the tree level as a key
          if usename:
              path[name] = child
          else:
              path[level] = child
          # Recurse into the next level
          yield from walk(tail, level + 1, path, usename)
  
imports: import os
  import sys
  import pickle
  from collections import defaultdict
  import re
  from copy import deepcopy
  from glob import glob
  from pathlib import Path
  from traceback import format_exception
  from hashlib import sha1
  from functools import reduce
  import numpy
  from ...None import logging, config
  from ...utils.filemanip import indirectory, relpath, fname_presuffix, ensure_list, get_related_files, save_json, savepkl, loadpkl, write_rst_header, write_rst_dict, write_rst_list
  from ...utils.misc import str2bool
  from ...utils.functions import create_function_from_source
  from ...interfaces.base.traits_extension import rebase_path_traits, resolve_path_traits, OutputMultiPath, isdefined, Undefined
  from ...interfaces.base.support import Bunch, InterfaceResult
  from ...interfaces.base import CommandLine
  from ...interfaces.utility import IdentityInterface
  from ...utils.provenance import ProvStore, pm, nipype_ns, get_id
  from inspect import signature
label_desc: Use image node_id 19 for calling a global function with example usage: walk(children, level, path, usename) without return types