'Mark all executable source lines in fn as executed 0 times.'

def find_source_lines(self):

    strs = trace.find_strings(self.filename)
    lines = trace.find_lines_from_code(self.fn.func_code, strs)
    self.firstcodelineno = sys.maxint
    for lineno in lines:
        self.firstcodelineno = min(self.firstcodelineno, lineno)
        self.sourcelines.setdefault(lineno, 0)
    if (self.firstcodelineno == sys.maxint):
        self.firstcodelineno = self.firstlineno
