local s_char = string.char;
local function char_to_hex(c)
return ("%02x"):format(c:byte())
end
local function hex_to_char(h)
return s_char(tonumber(h, 16));
end
local function to(s)
return s:gsub(".", char_to_hex);
end
local function from(s)
return s:gsub("..", hex_to_char);
end
return { to = to, from = from }