Method: Mark specific invitations as sent by invitation ID.

Method: Mark invitations as sent that are found by user_id, inviter_id, item id, and optional secondary item id, and class name.

Method: Mark specific invitations as accepted by invitation ID.

Method: Mark invitations as accepted that are found by user_id, inviter_id, item id, and optional secondary item id, and class name.

Method: Assemble the LIMIT clause of a get() SQL statement.

Method: Assemble query clauses, based on arguments, to pass to $wpdb methods.

Method: Get invitations, based on provided filter parameters.

Method: Get a count of total invitations matching a set of arguments.

Method: Update invitations.