Traceback (most recent call last):
  File "mypy/dmypy_server.py", line 229, in serve
  File "mypy/dmypy_server.py", line 272, in run_command
  File "mypy/dmypy_server.py", line 371, in cmd_recheck
  File "mypy/dmypy_server.py", line 528, in fine_grained_increment
  File "mypy/server/update.py", line 245, in update
  File "mypy/server/update.py", line 328, in update_one
  File "mypy/server/update.py", line 414, in update_module
  File "mypy/server/update.py", line 834, in propagate_changes_using_dependencies
  File "mypy/server/update.py", line 924, in reprocess_nodes
  File "mypy/server/astdiff.py", line 160, in snapshot_symbol_table
  File "mypy/server/astdiff.py", line 226, in snapshot_definition
AssertionError: <class 'mypy.nodes.ParamSpecExpr'>