print( and )          --

 print(nil and )       -- nil

 print(false and )     -- false

 print( or )           --

 print(false or )       --

 print(( and ) or )      --

 print((false and ) or )  --

 print(( and false) or )  --

 print(not nil)      -- ture

 print(not false)    -- true

 print(not )        -- false

 print(not not nil)  -- false

 x =

 v =

 y = x or v

 print(y)  --