-- Coerce T to be a table.
-- If T is a table, return it.  If not, return a blank table.
function table.coerce(t)
    if type(t) == "table" then
        return t
    else
        return {}
    end
end

-- Clear the table out.  Deletes all keys, removes any metatable.
-- TODO: this doesn't work on tables that have __metatable metamethod.
function table.rawclear(t)
    for k in pairs(t) do
        rawset(t, k, nil)
    end
    setmetatable(t, nil)
    return t
end