# File lib/ice_cube/time_util.rb, line 162
    def self.sym_to_wday(sym)
      DAYS.fetch(sym) do |k|
        DAYS.values.detect { |i| i.to_s == k.to_s } or
        raise ArgumentError, "Expecting Integer or Symbol value for weekday. " \
                             "No such weekday: #{k.inspect}"
      end
    end