polars 1.44.2, python 3.12.13, arm64

[1. lazy left join, row order]
  rows 2,000,000, same order as input: True, first ids [0, 1, 2, 3, 4]
  maintain_order='left': same order as input: True

[2. Int64 + UInt64]
  dtype Float64, value 9007199254740992.0  (exact answer 9007199254740994)

[3. cs.numeric() & pl.col('x')]
  columns ['x'] values [{'x': 1}, {'x': 2}]

[4. concat(how='horizontal') with heights 3 and 2]
   [{'a': 1, 'b': 10}, {'a': 2, 'b': 20}, {'a': 3, 'b': None}]

[5. explode() with an empty list]
  rows 3 [{'id': 1, 'tags': 'a'}, {'id': 1, 'tags': 'b'}, {'id': 2, 'tags': None}]

[6. int column .is_in([1.0, 2.5])]
   [1]

[7. df.melt()]
   [{'id': 1, 'variable': 'a', 'value': 2}]