$ go run -race main.go
==================
WARNING: DATA RACE
Read at 0x000000709670 by goroutine 8:
  runtime.convT2Eslice()
      /usr/local/go/src/runtime/iface.go:293 +0x0
  main.handleConn.func2()
      /home/konstantin/go/src/blockchain-tutorial/networking/main.go:100 +0x108

Previous write at 0x000000709670 by goroutine 11:
  main.handleConn.func1()
      /home/konstantin/go/src/blockchain-tutorial/networking/main.go:134 +0x758

Goroutine 8 (running) created at:
  main.handleConn()
      /home/konstantin/go/src/blockchain-tutorial/networking/main.go:97 +0x251

Goroutine 11 (running) created at:
  main.handleConn()
      /home/konstantin/go/src/blockchain-tutorial/networking/main.go:74 +0x21f
==================