Add length expression
Add NRows expression
Implement NRows for different backends
Clean up star imports
Move to reductions
Rename NRows -> nrows
Use None instead of {}
Import cleanup
Move to reductions
Axis is already there
Make nrows a property on tabular things
Use nelements() and nrows property
Remove the NRows class
Add better docstring
Add nrows with nunique
Implement SQL nelements
No parens!
Axis 0 (not a tuple) should be allowed
Use selectable not table
Add distinct nrows expression to test_comprehensive