code: def print_children(data_file, group='/'):
      
      base = data_file.get_node(group)
      print ('Groups in:\n  %s\n' % base)
  
      for node in base._f_walk_groups():
          if node is not base:
              print ('    %s' % node)
  
      print ('\nLeaf-nodes in %s:' % group)
      for node in base._v_leaves.itervalues():
          info = node.shape
          if len(info) == 0:
              info = node.read()
          print ('\t%s, %s' % (node.name, info))
          if len(node.title) > 0:
              print ('\t    %s' % node.title)
docs: Print all the sub-groups in `group` and leaf-nodes children of `group`.
  
      Parameters:
          data_file (pytables HDF5 file object): the data file to print
          group (string): path name of the group to be printed.
              Default: '/', the root node.