Part of lp.registry.interfaces.person View In Hierarchy
| Method | constraint | See IField. |
| Method | _getTeam | Return the context if it is a team or None. |
| Method | _validate | Ensure the TeamMembershipPolicy is valid for state of the team. |
Returns True if the team can change its membership policy to the
TeamMembershipPolicy, otherwise raise TeamMembershipPolicyError.