Function ruma_state_res::event_auth::valid_membership_change

pub fn valid_membership_change<E, F>(
    state_key: &str, 
    user_sender: &UserId, 
    content: Value, 
    prev_event: Option<Arc<E>>, 
    current_third_party_invite: Option<Arc<E>>, 
    fetch_state: F
) -> Result<bool> where
    E: Event,
    F: Fn(&EventType, &str) -> Option<Arc<E>>, 

Does the user who sent this member event have required power levels to do so.

• user - Information about the membership event and user making the request.
• prev_event - The event that occurred immediately before the user event or None.
• auth_events - The set of auth events that relate to a membership event. this is generated by calling auth_types_for_event with the membership event and the current State.