Performance result with differnet concat string in Golang.
+ go test -v -bench=. ./example36-performance/...
goos: linux
goarch: amd64
pkg: training/example36-performance
BenchmarkString01
BenchmarkString01-48 17109832 69.8 ns/op 32 B/op 1 allocs/op
BenchmarkString02
BenchmarkString02-48 4786852 252 ns/op 64 B/op 3 allocs/op
BenchmarkString03
BenchmarkString03-48 122471509 9.71 ns/op 0 B/op 0 allocs/op
BenchmarkString04
BenchmarkString04-48 12525997 94.4 ns/op 48 B/op 2 allocs/op
BenchmarkString05
BenchmarkString05-48 7054936 175 ns/op 56 B/op 3 allocs/op
PASS
ok training/example36-performance 7.607s