merge.go
func Merge(dst, src interface{}, opts ...func(*Config)) error {
	return merge(dst, src, opts...)
}
func Merge(dst, src interface{}, opts ...func(*Config)) error {
	return merge(dst, src, opts...)
}
// Merge will fill any empty for value type attributes on the dst struct using corresponding
// src attributes if they themselves are not empty. dst and src must be valid same-type structs
// and dst must be a pointer to struct.
// It won't merge unexported (private) fields and will do recursively any exported field.