code: def __enter__(self):
      self.fp = open(self.fname, "ab", buffering=0)
  
file_path: ffcv/ffcv/memory_allocator.py
imports: import numpy
  from time import sleep
  from os import SEEK_END
  from multiprocessing import Value
  from .utils import align_to_page
  import ctypes
label_desc: Use image node_id 2 for calling the MemoryAllocator obj's underlying member method code with example usage: obj.__enter__() without return types