<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def define(self):
 """If DFA is empty, create a sink state"""

        if len(self.states) == 0:
            for char in self.alphabet:
                self.add_arc(0, 0, char)
                self[0].final = False