model = {
  { player = "Cliff", age = 35, gender = "male" },
  { player = "Ally", age = 36, gender = "female" },
  { player = "Jasmine", age = 13, gender = "female" },
  { player = "Lauren", age = 6.5, gender = "female" }
}

    function for_each_array(list, operation)
      for key, value in ipairs(list) do
        operation(value)
      end
    end
    
    function filter_if(list, predicate)
      return function(value)
        if(predicate(value)) then
          list[#list + 1] = value
        end
      end
    end
    
    local list = {}
    for_each_array(model, filter_if(list, function(each) return each.age < 30 end))