The tutorial that I'm following to install my scanner asked me to post
the entry I created in libsane.usermap if my model wasn't found:
# Epson Corp.|Perfection 3490
libusbscanner 0x0003 0x04b8 0x0122 0x0000 0x0000
0x00 0x00 0x00 0x00 0x00
0x00 0x00000000