    # File lib/rbot/core/utils/filters.rb, line 103
        def register_filter(name, group=nil, &block)
          raise "No block provided" unless block_given?
          @filters ||= {}
          tlkey = global_filter_name(name, group)
          key = name.to_sym
          if has_filter?(tlkey)
            debug "Overwriting filter #{tlkey}"
          end
          @filters[tlkey] = DataFilter.new(&block)
          if group
            gkey = group.to_sym
            @filter_group ||= {}
            @filter_group[gkey] ||= {}
            if @filter_group[gkey].key?(key)
              debug "Overwriting filter #{key} in group #{gkey}"
            end
            @filter_group[gkey][key] = @filters[tlkey]
          end
        end