gistfile1.lua

function staff.callFunctionForEachEmployee(functionName, ...)
  if employee_instances then
    for _,employee in pairs(employee_instances) do
      employee[functionName](employee, ...)
    end
  end
end

-- or, for a more general approach
function callMethodOnEach(objects, method, ...)
  for _,object in pairs(objects) do
    object[method](object, ...)
  end
end