extensions/ipynb/src/notebookImagePaste.ts/CopyPasteEditProvider/getCellFromCellDocument
class CopyPasteEditProvider:	private getCellFromCellDocument(cellDocument: vscode.TextDocument): vscode.NotebookCell | undefined {
		for (const notebook of vscode.workspace.notebookDocuments) {
			if (notebook.uri.path === cellDocument.uri.path) {
				for (const cell of notebook.getCells()) {
					if (cell.document === cellDocument) {
						return cell;
					}
				}
			}
		}
		return undefined;
	}