Create nested structures with maps of maps:
users := make(map[string]map[string]string)
// Must initialize inner map before use
users["alice"] = make(map[string]string)
users["alice"]["email"] = "alice@example.com"
users["alice"]["role"] = "admin"
Be careful: each inner map must be initialized separately. Accessing a missing outer key returns nil, and writing to that nil map panics.