How "model.Rates" works ?

[Isolator-1]

I am wondering how "model.Rates" works.

For example :

vulname = m.VulnerabilityInfo(
    ... 
   rates=m.Rates(successRate=1.0)
),

I couldn't find where the variable "successRate" is used to calculate whether an exploitation succeeds or not.
( I means : When I tried to define successRates as 0.0 , the vulneraility still exploits successfully. )