class_docstr: Pattern for a mutable list-like object shareable via a shared
  memory block.  It differs from the built-in list type in that these
  lists can not change their overall length (i.e. no append, insert,
  etc.)
  
  Because values are packed into a memoryview as bytes, the struct
  packing format for any storable value must require no more than 8
  characters to describe its format.
docstr: The struct packing format used for the values' packing formats.
docstr_tok: ["The","struct","packing","format","used","for","the","values","'","packing","formats","."]
code: def _format_packing_metainfo(self):
      "The struct packing format used for the values' packing formats."
      return "8s" * self._list_len
  
imports: from functools import partial
  import mmap
  import os
  import errno
  import struct
  import secrets
label_desc: Use image node_id 13 for calling the ShareableList obj's underlying member method code with example usage: obj._format_packing_metainfo() and returns: unknown