cut/get a part of string lua (item name script)

function getRarity(str)
    print("starts getRarity")
    local value = 0
    local n = str:match("%[(.-)%]")
    print("rarity:")
    print(n)
    if n == "RARE" then
       value = 1
    elseif n == "EPIC" then
       value = 2
    elseif n == "LEGENDARY" then
       value = 3
    end
    print("value:")
    print(value)
    print("ends getRarity")...