" Stitched into the bag’s side were several new lines of glowing red runic script.
“What does it say?” Alex asked.
“Oh, a few technical runes.” Blitz’s eyes crinkled with satisfaction. “Magic nuts and
bolts, terms and conditions, the end-user agreement. But there at the bottom, it says:
‘EMPTYLEATHER, a bag completed by Blitzen, son of Freya. Jack helped.’”
“I wrote that!” Jack said proudly. “I helped! "

― Rick Riordan , The Hammer of Thor (Magnus Chase and the Gods of Asgard, #2)