LeverVariable.budget_contribution

LeverVariable.budget_contribution(z)

Monetary amount this variable draws from the shared budget.

Returns None by default, for a variable optimized in its own units: a discount depth is not money. A variable that spends from the pot returns that spend, and the default budget-sum constraint totals every such contribution.

The amount must follow the same convention as the media budgets, which are per-period rates rather than totals over the horizon, since the constraint sums the contributions directly.