def format_params(params)
      res = {}
      params
        .split(",")
        .each do |attribute|
        sort_sign = attribute =~ /\A[+-]/ ? attribute.slice!(0) : "+"
        res[attribute.to_sym] = SORT_ORDER[sort_sign]
      end
      res
    end
def format_params(params)
      res = {}
      params
        .split(",")
        .each do |attribute|
        sort_sign = attribute =~ /\A[+-]/ ? attribute.slice!(0) : "+"
        res[attribute.to_sym] = SORT_ORDER[sort_sign]
      end
      res
    end
input: "-email,first_name"
 return: { email: :desc, first_name: :asc }