execute example in at/basic, get an error

**What happened**: go run main.go , at at/basic, get error:
at/basic/main.go:38:2: undefined: sampleInsert
at/basic/main.go:41:2: undefined: sampleInsertOnUpdate
at/basic/main.go:44:2: undefined: sampleSelectForUpdate

**What you expected to happen**:
running normally

**How to reproduce it (as minimally and precisely as possible)**:
may be in my golang version: go version go1.20.5 darwin/amd64

**Anything else we need to know?**: no

Start with at/basic/main.go and inspect the references at lines 38, 41, and 44 to determine why sampleInsert, sampleInsertOnUpdate, and sampleSelectForUpdate are undefined. Run go run main.go from at/basic using the reported Go version; done means the example runs without these compilation errors.

Written by the indexing model from the issue text.