<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def featuretypes(self):
 """ Iterate over feature types found in the database. Returns ------- A generator object that yields featuretypes (as strings) """

        c = self.conn.cursor()
        c.execute(
            '''
            SELECT DISTINCT featuretype from features
            ''')
        for i, in c:
            yield i