add __call__ to AtIndexer

[ASEM000]

No description provided.

[codecov-commenter]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (4e9e073) 95.05% compared to head (38ad411) 94.97%.

Files	Patch %	Lines
sepes/_src/tree_pprint.py	72.72%	6 Missing ⚠️
sepes/_src/tree_index.py	97.43%	1 Missing ⚠️
tests/test_index.py	96.96%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #7      +/-   ##
==========================================
- Coverage   95.05%   94.97%   -0.09%     
==========================================
  Files          13       13              
  Lines        2265     2308      +43     
==========================================
+ Hits         2153     2192      +39     
- Misses        112      116       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.