The units CF property.
This property is a mirror of the units stored in the Units attribute.
Examples
>>> c.units = 'degrees_east'
>>> c.units
'degree_east'
>>> del c.units
>>> f.setprop('units', 'days since 2004-06-01')
>>> f.getprop('units')
'days since 2004-06-01'
>>> f.delprop('units')