The history CF property.
Examples
>>> f.history = 'created on 2012/10/01'
>>> f.history
'created on 2012/10/01'
>>> del f.history
>>> f.setprop('history', 'created on 2012/10/01')
>>> f.getprop('history')
'created on 2012/10/01'
>>> f.delprop('history')