addition of new mutation types

[awast]

Hi, I would like to request that if it possible to add new mutation types for example: _from script:

default rename is to collapse ins and del to indel

if rename is None:
    rename = {'Nonsense_Mutation': 'Nonsense', 'In_Frame_Del': 'In frame indel', 'In_Frame_Ins': 'In frame indel',
              'Frame_Shift_Del': 'Frameshift indel', 'Missense_Mutation': 'Missense', 'Splice_Site': 'Splice site', 'Frame_Shift_Ins': 'Frameshift indel'}__

like above is it possible to add some addittional mutation names like for :

1. startloss
2. startgain 3.stoploss please suggest how can i add these names to mutation types