verifier is a package that makes your Go code a bit nicer when you need to validate multiple things before running a block of code.

verify.That(transfer != nil, "transfer can't be nil")
verify.That(person != nil, "person can't be nil")
if verify.GetError() != nil {
  return nil, verify.GetError()

They don't say it, but this is, basically, a monad. The package exists because Go doesn't have exceptions or powerful enough type system ๐Ÿ‘€ Anyway, the library is pretty helpful, remember it when you next time need to validate a lot of things.