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diff --git a/tools/eslint/node_modules/is-alphabetical/index.js b/tools/eslint/node_modules/is-alphabetical/index.js
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+/**
+ * @author Titus Wormer
+ * @copyright 2016 Titus Wormer
+ * @license MIT
+ * @module is-alphabetical
+ * @fileoverview Check if a character is alphabetical.
+ */
+
+'use strict';
+
+/* eslint-env commonjs */
+
+/* Expose. */
+module.exports = alphabetical;
+
+/**
+ * Check whether the given character code, or the character
+ * code at the first character, is alphabetical.
+ *
+ * @param {string|number} character
+ * @return {boolean} - Whether `character` is alphabetical.
+ */
+function alphabetical(character) {
+  var code = typeof character === 'string' ?
+    character.charCodeAt(0) : character;
+
+  return (code >= 97 && code <= 122) || /* a-z */
+    (code >= 65 && code <= 90); /* A-Z */
+}