The energy budget checker

You will write the model of the energy budget of an ecosystem, and test that all the energy is accounted for.

The idea. The NPP is the GPP minus the respiration of the plants. T2, T3 and T4 get $10\%$ of the level below. The loss of each consumer level is its energy minus what it passes on. A share of the loss is respired. The rest goes to the detritus. The decomposers give off all the detritus as heat.

Your tasks.

1. Finish npp. It gives the net primary productivity.
2. Finish consumer_levels. It gives the list of the energies of T2, T3 and T4.
3. Finish total_heat. It gives all the heat that leaves the ecosystem.