# File lib/active_support/time_with_zone.rb, line 172
    def -(other)
      if other.acts_like?(:time)
        utc - other
      else
        result = utc.acts_like?(:date) ? utc.ago(other) : utc - other rescue utc.ago(other)
        result.in_time_zone(time_zone)
      end
    end