dev(hansbug): add documentation && try do slightly optimization

[HansBug]

#55

[codecov]

Codecov Report

Merging #61 (82b722c) into main (92bbe31) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #61      +/-   ##
==========================================
- Coverage   99.26%   99.25%   -0.01%     
==========================================
  Files          35       35              
  Lines        2168     2152      -16     
==========================================
- Hits         2152     2136      -16     
  Misses         16       16              

Flag	Coverage Δ
unittests	99.25% <100.00%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
treevalue/tree/general/general.py	100.00% <ø> (ø)
treevalue/tree/tree/service.pyx	100.00% <ø> (ø)
treevalue/tree/common/storage.pyx	100.00% <100.00%> (ø)
treevalue/tree/tree/tree.pyx	100.00% <100.00%> (ø)

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