json.encode not working correctly

[usyntax]

Hello,

How i can use json.encode() function? I tried use this script:

Code:

test = {
  one='first',two='second',three={2,3,5}
}

jsonTest = json.encode(test)

but i get error: 

Code:

attempt to index global 'json' (a nil value)
stack traceback:
User script:37: in main chunk