Returning value allow do `var _ = AddHookType(xxx)`.

DebugHook used to debug config decode.

Decodes conf to result.

"host:port" or ":port".

Map maps with overwrite fields from src to dst.

RegisterCustom used to set custom validation check hooks on specific types, that will be called on such type validation, even if it is nested field.

StringToAbstractValidation wraps StringValidation into validator.Func.

StringToDataSizeHook converts string to datasize.Single.

StringToIPHook converts string to net.IP.

StringToURLHook converts string to url.URL or *url.URL.

VariableInjectHook injects values into ${VAR_NAME} placeholders.