critical[multiple-definitions]: Variable 'x' is defined in multiple cells
 --> tests/_lint/test_files/multiple_definitions.py:9:1
   9 |     print(1)
  10 |     x = 1
     |     ^
  11 |     return
   ...
  15 | def _():
  16 |     x = 2  # This should trigger MR001 - multiple definitions
     |     ^
  17 |     return
hint: Variables must be unique across cells. Alternatively, they can be private with an underscore prefix (i.e. `_x`.)
