class_docstr: Mode-checking helper functions.
class_docstr_tok: ["Mode-checking","helper","functions","."]
code: def _check_not_closed(self):
      if self.closed:
          raise ValueError("I/O operation on closed file")
  
file_path: cpython/Lib/_compression.py
imports: import io
  import sys
label_desc: Use image node_id 1 for calling the BaseStream obj's underlying member method code with example usage: obj._check_not_closed() without return types