Player sensor Computercraft

local p = peripheral.wrap("top")

username = info[1].name
pos = p.getPlayerByName(username).position

while true do
  info = p.getPlayers()
  if info ~= nil then
    for key, value in pairs(info) do
      username = info[1].name
      pos = p.getPlayerByName(username).position
      if pos then
        p.getPlayers()
        if pos.x >= -4 and pos.x <= 4
        and pos.y >= -1 and pos.y <= 5
        and pos.z >= -4 and pos.z <= 4 then
          if ((username == "ShitFace") or (username == "FaceShit")) then
            redstone.setOutput("back", true)
          else
            redstone.setOutput("back", true)
          end
        else
          redstone.setOutput("back", false)
        end
      else
      redstone.setOutput("back", false)
      end
    end
  end
end