Encoder is an interface implemented by any type that wishes to encode itself into URL values in a non-standard way.

customEncodedInt is an int with a custom URL encoding

customEncodedInt is an int with a custom URL encoding defined on its pointer value.

customEncodedStrings is a slice of strings with a custom URL encoding

tagOptions is the string following a comma in a struct field's "url" tag, or the empty string. It does not include the leading comma.