code: def test_memmap():
      with tmpfile("npy") as fn:
          with open(fn, "wb") as f:  # touch file
              pass
          x = np.memmap(fn, shape=(5, 5), dtype="i4", mode="readwrite")
          x[:] = 5
  
          header, frames = serialize(x)
          if "compression" in header:
              frames = decompress(header, frames)
          y = deserialize(header, frames)
  
          np.testing.assert_equal(x, y)
  
imports: from __future__ import annotations
  from zlib import crc32
  import pytest
  from dask.utils import ensure_bytes, tmpfile
  from distributed.protocol import decompress, deserialize, dumps, loads, msgpack, serialize, to_serialize
  from distributed.protocol.compression import maybe_compress
  from distributed.protocol.numpy import itemsize
  from distributed.protocol.utils import BIG_BYTES_SHARD_SIZE
  from distributed.system import MEMORY_LIMIT
  from distributed.utils import nbytes
  from distributed.utils_test import gen_cluster
label_desc: Use image node_id 7 for calling a global function with example usage: test_memmap() without return types