CloudEvent registers a CloudEvent function that becomes the function handler served at "/" when environment variable `FUNCTION_TARGET=name`.

HTTP registers an HTTP function that becomes the function handler served at "/" when environment variable `FUNCTION_TARGET=name`.

Typed registers a Typed function that becomes the function handler served at "/" when environment variable `FUNCTION_TARGET=name` This function takes a strong type T as an input and can return a strong type T, built in types, nil and/or error as an output.