def limit(count)
      raise InvalidPageSize unless count && count > 0
      Specification.new(reader, result.dup { |r| r.count = count })
    end
def limit(count)
      raise InvalidPageSize unless count && count > 0
      Specification.new(reader, result.dup { |r| r.count = count })
    end
Limits the query to specified number of events.
 {http://railseventstore.org/docs/read/ Find out more}.

 @param count [Integer] maximal number of events to retrieve
 @return [Specification]