<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def copy(self, key):
 """Copy the set to another key and return the new Set. WARNING: If the key exists, it overwrites it. """

        copy = Set(key=key, db=self.db)
        copy.clear()
        copy |= self
        return copy