:type cnfs: :py:class`CnfList`
When the instance of a cnfvar is -1, the backend initializes it
- automatically. However it starts on 1, whereas many variables are not
+ automatically. However, it starts on 1, whereas many variables are not
allowed to start on one (those that are meant to be unique, f.e.).
This method can be used in child classes to use an alternative scheme,
however for performance reasons the base API class uses the default and