Banned Item List text scroller

local function pcenter(input)
local size={term.getSize()}
local pos={term.getCursorPos()}
if input then
term.setCursorPos(size[1]/2-string.len(input)/2,pos[2])
write(input)
else
print("oops")
print(pos[2])
print(input)
end
end

local function scrollat(input,starty,endy,delay)

if not input then
term.clear()
term.setCursorPos(1,1)
print("USAGE: scrollat(table-of-scrolling-values,y-value-at-which-the-nest-starts,y-value-at-which-the-nest-stops,the-time-in-seconds-between-each-scroll)")
end

if type(input)~="table" then
print("incorrect input")
return nil
end

delay=delay or 1

local scrolled=0
while true do
for y=starty,endy do
term.setCursorPos(1,y)
local current=y+scrolled-starty+1
if current>#input then
current=current-#input
end
local size={term.getSize()}
for a=1,size[1]-1 do
write(" ")
end
pcenter(input[current])
end
scrolled=scrolled+1
if scrolled>#input then
scrolled=1
end
sleep(delay)
end
end

local tBanned = {"Hyper Kinetic Lens", "Red Matter Furnace", "Computercraft", "Volcanite Amulet", "Black Hole Chest", "Mercurial Eye", "Black Hole Band", "Watch of Flowing Time", "Evertide Amulet", "Nova Catalyst", "Wireless Tracker", "Destruction Catalyst", "Wireless Transceiver", "Wireless Sniffer", "Wireless Remote", "Wireless Map", "World Anchor", "Rings Of Arcana", "Nova Cataclysm", "Gem Armor", "Void Ring", "Nukes, TNT, ITNT, Dynamite, Sticky Dynamite", "Alchemical Tome", "DarkMatter Pedestal", "Teleport Tether", "REP", "Mining Laser", "Crafting Bench 3", "All Energy Collectors","Block Breaker", "Terraformer","RM Tools & Armor", "DM Tools & Armor", "Philosopher's Stone"}
term.clear()
term.setCursorPos(1,1)
pcenter("--Banned List--")
local size={term.getSize()}
scrollat(tBanned,3,size[2]-1,1)