sane.Option doesn't properly handle buttons named "scan"

I have a couple of scanners (a Fujitsu SnapScan 1500 and a Canon CanoScan LiDE 210) that have front-panel buttons that can initiate scans. Unfortunately, the primary scan buttons are named "scan" and that collides with the bound method to ask the scanner to begin scanning.

>>> import sane
>>>
>>> sane.init()
(16777247, 1, 0, 31)
>>> sane.get_devices()
[('genesys:libusb:001:008', 'Canon', 'LiDE 210', 'flatbed scanner'), ('fujitsu:ScanSnap S1500:56050', 'FUJITSU', 'ScanSnap S1500', 'scanner')]
>>>
>>> scanner = sane.open('fujitsu:ScanSnap S1500:56050')
>>> scanner.opt['scan']

Name:      scan
Cur value: <bound method SaneDev.scan of <sane.SaneDev object at 0x7f8567e60f40>>
Index:     91
Title:     Scan button
Desc:      Scan button
Type:      TYPE_BOOL
Unit:      UNIT_NONE
Constr:    None
active:    yes
settable:  no

Modifying sane.py on line 307 to change the method name from scan to, say, doscan "fixes" the issue for me:

>>> scanner.opt['scan']

Name:      scan
Cur value: 0
Index:     91
Title:     Scan button
Desc:      Scan button
Type:      TYPE_BOOL
Unit:      UNIT_NONE
Constr:    None
active:    yes
settable:  no

I'm not sure what the proper way to fix this for real. :/

Start by reading sane.py around line 307 and the SaneDev.scan method, then reproduce the collision with scanner.opt['scan'] using the example in the issue. Determine how option names and SaneDev methods are exposed together; done means the scan button remains accessible as an option while the scanner can still be asked to begin scanning.