extensions/git/src/git-base.ts/GitBaseApi/getAPI
class GitBaseApi:	static getAPI(): GitBaseAPI {
		if (!this._gitBaseApi) {
			const gitBaseExtension = extensions.getExtension<GitBaseExtension>('vscode.git-base')!.exports;
			const onDidChangeGitBaseExtensionEnablement = (enabled: boolean) => {
				this._gitBaseApi = enabled ? gitBaseExtension.getAPI(1) : undefined;
			};

			gitBaseExtension.onDidChangeEnablement(onDidChangeGitBaseExtensionEnablement);
			onDidChangeGitBaseExtensionEnablement(gitBaseExtension.enabled);

			if (!this._gitBaseApi) {
				throw new Error('vscode.git-base extension is not enabled.');
			}
		}

		return this._gitBaseApi;
	}