splice

Transfer count bytes from one pipe to a descriptor or vice versa.

  src
    Source file descriptor.
  dst
    Destination file descriptor.
  count
    Number of bytes to copy.
  offset_src
    Starting offset in src.
  offset_dst
    Starting offset in dst.
  flags
    Flags to modify the semantics of the call.

If offset_src is None, then src is read from the current position;
respectively for offset_dst. The offset associated to the file
descriptor that refers to a pipe must be None.