src/vs/workbench/contrib/debug/common/debugModel.ts/Expression/evaluate
class Expression:	async evaluate(session: IDebugSession | undefined, stackFrame: IStackFrame | undefined, context: string, keepLazyVars?: boolean): Promise<void> {
		this.available = await this.evaluateExpression(this.name, session, stackFrame, context, keepLazyVars);
	}