code: def read_long(fo):
      """variable-length, zig-zag encoding."""
      c = fo.read(1)
      b = ord(c)
      n = b & 0x7F
      shift = 7
      while (b & 0x80) != 0:
          b = ord(fo.read(1))
          n |= (b & 0x7F) << shift
          shift += 7
      return (n >> 1) ^ -(n & 1)
  
file_path: dask/dask/bag/avro.py
imports: from __future__ import annotations
  import io
  import uuid
  from fsspec.core import OpenFile, get_fs_token_paths, open_files
  from fsspec.utils import read_block
  from fsspec.utils import tokenize
  from dask.highlevelgraph import HighLevelGraph
label_desc: Use image node_id 1 for calling a global function with example usage: read_long(fo) and returns: unknown