code: def _block(arrays, max_depth, result_ndim, depth=0):
      """
      Internal implementation of block based on repeated concatenation.
      `arrays` is the argument passed to
      block. `max_depth` is the depth of nested lists within `arrays` and
      `result_ndim` is the greatest of the dimensions of the arrays in
      `arrays` and the depth of the lists in `arrays` (see block docstring
      for details).
      """
      if depth < max_depth:
          arrs = [
              _block(arr, max_depth, result_ndim, depth + 1)
              for arr in arrays
          ]
          return _nx.concatenate(arrs, axis=-(max_depth - depth))
      else:
          # We've 'bottomed out' - arrays is either a scalar or an array
          # type(arrays) is not list
          return _atleast_nd(arrays, result_ndim)
  
imports: from __future__ import division, absolute_import, print_function
  import functools
  import operator
  import types
  import warnings
  from .None import numeric
  from .None import overrides
  from .numeric import array, asanyarray, newaxis
  from .multiarray import normalize_axis_index
label_desc: Use image node_id 20 for calling a global function with example usage: _block(arrays, max_depth, result_ndim, depth) and returns: _nx, _atleast_nd