我想在下面显示的输出中添加一个key-val对，其编号为2，site-label为co2。

{:correct? false,:training-countdown nil,:site-communication {0 [],1 [],2 [],3 (0 1),4 (3 2)},:site-label :t-<<:temperature-:humidity_i3>-:co2_i4>,:agreement 478/739,:breakdown
 {0
  {:training-countdown nil,:site-label :temperature,:agreement 1,:site-order 0,:transformed-confidence 0.6367035786260278,:confidence-ma 0.86235090749618,:raw-votes (0.17910252984637456 0.10219403555517105),:id 10001,:class 0,:raw-confidence 0.17910252984637456,:site-type :p-site,:quantile 139/1000,:confidence 0.6367035786260278,:process-time {:cpu-nano 0,:wall-nano 14500}},1
  {:training-countdown nil,:site-label :humidity,:transformed-confidence 0.7396347578595606,:confidence-ma 0.7673990631272951,:raw-votes (0.05875164784557538 0.020681676807254086),:raw-confidence 0.05875164784557538,:quantile 273/1000,:confidence 0.7396347578595606,:wall-nano 26600}},2
  {:training-countdown nil,:site-label :co2,:transformed-confidence 0.6885013017580619,:confidence-ma 0.8687745984384241,:raw-votes (6.209281474901374E-4 2.809265707284352E-4),:raw-confidence 6.209281474901374E-4,:quantile 79/1000,:confidence 0.6885013017580619,:wall-nano 14400}},3
  {:training-countdown nil,:site-label :t-<:temperature-:humidity_i3>,:agreement 498/499,:site-order 1,:transformed-confidence 0.7146049092604565,:confidence-ma 0.9331555208607589,:raw-votes (220.42790579127143 551.9326320865079),:class 1,:raw-confidence 551.9326320865079,:site-type :t-site,:quantile 9/100,:confidence 0.7146049092604565,:wall-nano 241300}},4
  {:training-countdown nil,:site-order 2,:transformed-confidence 0.932189769224312,:confidence-ma 0.845843308389129,:raw-votes (51.39818941403593 706.5728250787176),:raw-confidence 706.5728250787176,:quantile 317/500,:confidence 0.932189769224312,:wall-nano 283700}}},:truth 0,:candidate-results
 {-1
  {:training-countdown nil,:wall-nano 283700}}