- Functional modules could be employed by their main flows to adapt to the unbalanced status of two balance pairs (carbon flow versus electron flow and electron flow versus energy flow). The color and size of the nodes and arrows represented the amount and direction (green, providing; red, consuming; yellow, interconverting) of the contribution to each flow. 1-pro primary providing, 2-pro secondary providing, 1-con primary consuming, 2-con secondary consuming, inter interconverting