src/vs/workbench/api/common/extHostTerminalService.ts/BaseExtHostTerminalService/$acceptActiveTerminalChanged
class BaseExtHostTerminalService:	public async $acceptActiveTerminalChanged(id: number | null): Promise<void> {
		const original = this._activeTerminal;
		if (id === null) {
			this._activeTerminal = undefined;
			if (original !== this._activeTerminal) {
				this._onDidChangeActiveTerminal.fire(this._activeTerminal);
			}
			return;
		}
		const terminal = this._getTerminalById(id);
		if (terminal) {
			this._activeTerminal = terminal;
			if (original !== this._activeTerminal) {
				this._onDidChangeActiveTerminal.fire(this._activeTerminal.value);
			}
		}
	}