https://go.dev/doc/go1.19 > The new function [TextVar](https://go.dev/pkg/flag/#TextVar) defines a flag with a value implementing [encoding.TextUnmarshaler](https://go.dev/pkg/encoding/#TextUnmarshaler), allowing command-line flag variables to have types such as [big.Int](https://go.dev/pkg/math/big/#Int), [netip.Addr](https://go.dev/pkg/net/netip/#Addr), and [time.Time](https://go.dev/pkg/time/#Time). - https://pkg.go.dev/flag#TextVar
https://go.dev/doc/go1.19