s.lua

r:stream():line() --> `err`, `Slice`

-- a slice is a restricted `off`, `len` window into a buffer. offers all methods buffer does. 
-- is bump / growable, if `len` extends to the end of the buffer's current contents.

-- this allows you to make use of the line without incurring and additional copy
-- you call `:trim` when done with the line.

-- buffer (and so slice) will get two new methods

slice:string()  -- just a rename of take, effectively ffi.string(slice:value()) and :trims
slice:data()    -- returns copy as LeveeData, and :trims