code: def get_filetype(bytesbuf):
      """Detect compression type of bytesbuf.
  
      ZIP only. TODO: add others relevant to GDAL/OGR."""
      if bytesbuf[:4].startswith(b"PK\x03\x04"):
          return "zip"
      else:
          return ""
  
imports: from contextlib import ExitStack
  import logging
  import os
  import warnings
  from fiona import compat, vfs
  from fiona.ogrext import Iterator, ItemsIterator, KeysIterator
  from fiona.ogrext import Session, WritingSession
  from fiona.ogrext import buffer_to_virtual_file, remove_virtual_file, GEOMETRY_TYPES
  from fiona.errors import DriverError, DriverSupportError, GDALVersionError, SchemaError, UnsupportedGeometryTypeError, UnsupportedOperation
  from fiona.logutils import FieldSkipLogFilter
  from fiona.crs import CRS
  from fiona._env import get_gdal_release_name, get_gdal_version_tuple
  from fiona.env import env_ctx_if_needed
  from fiona.errors import FionaDeprecationWarning
  from fiona.drvsupport import driver_from_extension, supported_drivers, driver_mode_mingdal, _driver_converts_field_type_silently_to_str, _driver_supports_field
  from fiona.path import Path, vsi_path, parse_path
label_desc: Use image node_id 2 for calling a global function with example usage: get_filetype(bytesbuf) and returns: str, str