fix: imports

Author: MaksymStoianov

src/appsscript/sheets/getColumnLetterByPosition.ts

@@ -1,4 +1,4 @@
-import { getColumnLetterByIndex } from "@/appsscript";
+import { getColumnLetterByIndex } from "./getColumnLetterByIndex";
 
 /**
  * ## getColumnLetterByPosition

src/appsscript/sheets/isCellGridRange.ts

@@ -1,4 +1,4 @@
-import { nonNil } from "@/base";
+import { nonNil } from "../../base";
 import { GridRange } from "./types";
 
 /**

src/appsscript/sheets/nonSheet.ts

@@ -0,0 +1,19 @@
+import { isObject } from "../../base";
+
+/**
+ * ## isSheet
+ *
+ * Checks if the given value is a Google Apps Script [`Sheet`](https://developers.google.com/apps-script/reference/spreadsheet/sheet) object.
+ *
+ * @param       value - The value to check.
+ * @returns     `true` if the value is a {@link GoogleAppsScript.Spreadsheet.Sheet|Sheet} object, `false` otherwise.
+ * @see         [Class Sheet](https://developers.google.com/apps-script/reference/spreadsheet/sheet)
+ * @since       1.0.0
+ * @version     1.0.0
+ * @environment `Google Apps Script`, `Browser`
+ */
+export function isSheet(
+  value: unknown
+): value is GoogleAppsScript.Spreadsheet.Sheet {
+  return isObject(value) && value?.toString() === "Sheet";
+}