fixed referenced item

[Code-Hex]

• added comment for Reference method
• fixed some points to use Reference method

[codecov]

Codecov Report

Merging #8 (85a991f) into main (82f85aa) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main        #8   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          262       272   +10     
=========================================
+ Hits           262       272   +10     

Impacted Files	Coverage Δ
cache.go	100.00% <ø> (ø)
lru/lru.go	100.00% <100.00%> (ø)
simple/simple.go	100.00% <100.00%> (ø)

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