Dictionary tree (hard confirm)

local dictionary = {}

local function insertWord(dict, word)
    local head, tail = word:upper():match('^(%a)(%a*)$')
    if not head then return false; end
    if not dict[head] then dict[head] = {}; end
    if tail == '' then
        dict[head][''] = true
        return true
    else
        return insertWord(dict[head], tail)
    end
end

insertWord(dictionary, 'BAG')

if dictionary['B'] and dictionary['B']['A'] and dictionary['B']['A']['G'] and dictionary['B']['A']['G'][''] then
    print(true)
else
    print(false)
end