Trying to get logic honor if-statements to control output

Checkmk Exchange
4

This will not work, see comments inline

if line[0].isdigit():  # this checks for a number
            if line[0].find('Bugfix'):  # if it is a number it can not contain a string
                .....
            if ("Enhancement" in line[0] != True):  # can also not contain a string
               .....
            if "Security" in line[0]:  # and again can not contain a string
               ....