Struct cache example for Go

Source files are distributed under the BSD-style license.
About
The software is considered to be at an alpha level of readiness,
its extremely slow and allocates a lots of memory.
Benchmark
$ go test -count=1 -race -bench ./...
goos: linux
goarch: amd64
pkg: github.com/danil/rocacheexample
cpu: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
BenchmarkCache/cache-8 13396 89845 ns/op
PASS
ok github.com/danil/rocacheexample 2.143s