Shared Energy.

Under this scheme, when a cell issues an et_collect instruction to collect energy tokens from the environment, it first tries to collect spare tokens from its current grid position. However, if the grid position does not contain sufficient energy tokens, the cell then looks for other cells at the same grid position or in one of the eight neighbouring grid positions. If other cells exist in one of these nine locations, energy tokens will be extracted from the Energy Token Store of one (or more) of these (at random) until the cell has obtained the normal quota of energy tokens for one execution of et_collect (as defined by the global parameter number_of_energy_tokens_per_collect).