> [[a b]; [6 2] [1 4] [4 1]] | polars into-lazy | polars append -c ([[a b]; [6 2] [1 4] [4 1]] | polars into-df)
Error: nu::shell::cant_convert

  × Can't convert to NuDataFrame.
   ╭─[entry #1:1:49]
 1 │ [[a b]; [6 2] [1 4] [4 1]] | polars into-lazy | polars append -c ([[a b]; [6 2] [1 4] [4 1]] | polars into-df)
   ·                                                 ──────┬──────
   ·                                                       ╰── can't convert NuLazyFrameCustomValue to NuDataFrame
   ╰────