Hi, Please help,I am learning odoo 8 but hr_holiday module is written in v7,so evrythings getting messy...

i want to modify Hr_holidays module following if a person has applied for holiday on saturday and again applies for holiday on monday, then sunsday should also be counted as a holiday,that means instead of 2 holidays(saturday and monday) sunday shoul automatically be included and 3 leaves would be deducted from his leave quota.