Find Nearest Player

os.loadAPI("ocs/apis/sensor")
mySensor = sensor.wrap("left")

while true do
    targets = mySensor.getTargets()
    player = false;
    for k, v in pairs( targets ) do
        details = mySensor.getTargetDetails(k)
        if details ~= nil and details["IsPlayer"] ~= nil and details["IsPlayer"] then
            pos = details["Position"];
            dist = math.sqrt(math.pow(pos["X"],2) + math.pow(pos["Y"],2) + math.pow(pos["Z"],2))
            if dist <= 40 then
                player = true
            end
        end
    end

    if player then
        redstone.setOutput("right", true)
    else
        redstone.setOutput("right", false)
    end
end