internal/errd/wrap.go

+package errd
+
+import (
+	"fmt"
+)
+
+// Wrap wraps err with fmt.Errorf if err is non nil.
+// Intended for use with defer and a named error return.
+// Inspired by https://github.com/golang/go/issues/32676.
+func Wrap(err *error, f string, v ...interface{}) {
+	if *err != nil {
+		*err = fmt.Errorf(f+": %w", append(v, *err)...)
+	}
+}

internal/examples/README.md

+# Examples
+
+This directory contains more involved examples unsuitable
+for display with godoc.