Use an empty DataFrame for DataFrame indexing things & import/export cleanup

[krynju]

No description provided.

[codecov-commenter]

Codecov Report

Base: 95.83% // Head: 95.85% // Increases project coverage by +0.01% 🎉

Coverage data is based on head (ec8d476) compared to base (5fc7ec1).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   95.83%   95.85%   +0.01%     
==========================================
  Files          10       10              
  Lines         817      820       +3     
==========================================
+ Hits          783      786       +3     
  Misses         34       34              

Impacted Files	Coverage Δ
src/operations/dataframes_interface_utils.jl	94.33% <ø> (ø)
src/operations/groupby.jl	100.00% <ø> (ø)
src/operations/join.jl	100.00% <ø> (ø)
src/operations/join_interface.jl	100.00% <ø> (ø)
src/operations/operations.jl	98.46% <ø> (ø)
src/operations/dataframes_interface.jl	89.58% <100.00%> (ø)
src/table/dtable.jl	92.06% <100.00%> (+0.26%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.