Fix insert as sibling

[ilgiz-badamshin]

Siblings should stay on same level.

[codecov]

Codecov Report

Merging #20 (23c1e53) into master (7b2c234) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master      #20   +/-   ##
=======================================
  Coverage   56.12%   56.12%           
=======================================
  Files           2        2           
  Lines         433      433           
=======================================
  Hits          243      243           
  Misses        190      190           

Impacted Files	Coverage Δ
index.js	55.45% <0.00%> (ø)

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