code: def _copyfileobj_readinto(fsrc, fdst, length=COPY_BUFSIZE):
      """readinto()/memoryview() based variant of copyfileobj().
      *fsrc* must support readinto() method and both files must be
      open in binary mode.
      """
      # Localize variable access to minimize overhead.
      fsrc_readinto = fsrc.readinto
      fdst_write = fdst.write
      with memoryview(bytearray(length)) as mv:
          while True:
              n = fsrc_readinto(mv)
              if not n:
                  break
              elif n < length:
                  with mv[:n] as smv:
                      fdst_write(smv)
                  break
              else:
                  fdst_write(mv)
  
imports: import os
  import sys
  import stat
  import fnmatch
  import collections
  import errno
label_desc: Use image node_id 3 for calling a global function with example usage: _copyfileobj_readinto(fsrc, fdst, length) without return types