# File lib/ruote/storage/hash_storage.rb, line 102
    def delete(doc)

      drev = doc['_rev']

      raise ArgumentError.new("can't delete doc without _rev") unless drev

      synchronize do

        prev = get(doc['type'], doc['_id'])

        return true if prev.nil?

        doc['_rev'] ||= 0

        return prev if prev['_rev'] != drev

        @h[doc['type']].delete(doc['_id'])

        nil # success
      end
    end