'Returns a single player whose NFL GameCenter identifier equals
`playerid`. This probably isn\'t too useful, unless you\'re trying
to do ID mapping. (Players have different identifiers across NFL.com.)
If no such player with the given identifier is found, None is
returned.'

def playerid(self, playerid):

    for p in self:
        if (p.playerid == playerid):
            return p
    return None
