Question: in your opinion can a leader maintain a personal friendship...

In your opinion, can a leader maintain a personal friendship with some members of his or her work group without creating the perception of in-groups (those in his or her social circle) and out-groups (those outside his or her social circle)? Provide an example from a work or team environment you've been in or witnessed in which the leader and a team member/co-worker were good friends. How did it impact the team? What advice would you give to leaders who have good friends in a team they lead?