<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def select(self, element):
 """Add an element to the set of selected elements Proxy to internal set.add and sync field """

        self._field.validate_value(element)
        self._elements.add(element)
        self._sync_field()