lua - How does the buffer from the ws2812b module work? -

this example taken ws2812 documentation:

ws2812.init() local i, buffer = 0, ws2812.newbuffer(300, 4); buffer:fill(0, 0, 0, 0); tmr.create():alarm(50, 1, function()   = + 1   buffer:fade(2)   buffer:set(i % buffer:size() + 1, 0, 0, 0, 255)   ws2812.write(buffer) end) 

first of tried translate more readable , since use rgb , not rgbw leds, removed w component:

local numberofleds = 300 local bytesperled = 3 -- (r, g , b)  ws2812.init()  local local buffer = 0  ws2812.newbuffer(numberofleds, bytesperled) buffer:fill(255, 255, 255)  tmr.create():alarm(50, 1, function() -- repeat every 50 milliseconds     = + 1     buffer:fade(2)     buffer:set(i % buffer:size() + 1, 255, 255, 255)     ws2812.write(buffer) end) 

it doesn't make sense me, though. why buffer have fill method? mean didn't set 0? buffer = 0 translating incorrectly?
original code said local i, buffer = 0, ws2812.newbuffer(...); ...

the original code equivalent to

local = 0 local buffer = ws2812.newbuffer(300, 4); buffer:fill(0, 0, 0, 0); tmr.create():alarm(50, 1, function() 

in general,

local x,y,z = a,b,c 

is equivalent to

local x = local y = b local z = c 

see manual.