Proto api is not working in Lua5.2.3

["immanuel.beno@..." <immanuel.beno@...>]

> local proto_foo = Proto("test", "Test Protocol")

stdin:1: attempt to call global 'Proto' (a nil value)

stack traceback:

        stdin:1: in main chunk

        [C]: in ?

>

pls help to fix this issue 

Regards,
Beno K Immanuel
Chennai, India
Mob: +91 9940791964
Email:immanuel.beno@gmail.com