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backend/node_modules/date-fns/esm/isExists/index.d.ts

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+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+import { isExists } from 'date-fns'
+export default isExists

backend/node_modules/date-fns/esm/isExists/index.js

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+/**
+ * @name isExists
+ * @category Common Helpers
+ * @summary Is the given date exists?
+ *
+ * @description
+ * Checks if the given arguments convert to an existing date.
+ *
+ * @param {Number} year of the date to check
+ * @param {Number} month of the date to check
+ * @param {Number} day of the date to check
+ * @returns {Boolean} the date exists
+ * @throws {TypeError} 3 arguments required
+ *
+ * @example
+ * // For the valid date:
+ * const result = isExists(2018, 0, 31)
+ * //=> true
+ *
+ * @example
+ * // For the invalid date:
+ * const result = isExists(2018, 1, 31)
+ * //=> false
+ */
+export default function isExists(year, month, day) {
+  if (arguments.length < 3) {
+    throw new TypeError('3 argument required, but only ' + arguments.length + ' present');
+  }
+  var date = new Date(year, month, day);
+  return date.getFullYear() === year && date.getMonth() === month && date.getDate() === day;
+}

backend/node_modules/date-fns/esm/isExists/index.js.flow

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+// @flow
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+export type Interval = {
+  start: Date | number,
+  end: Date | number,
+}
+
+export type Locale = {
+  code?: string,
+  formatDistance?: (...args: Array<any>) => any,
+  formatRelative?: (...args: Array<any>) => any,
+  localize?: {
+    ordinalNumber: (...args: Array<any>) => any,
+    era: (...args: Array<any>) => any,
+    quarter: (...args: Array<any>) => any,
+    month: (...args: Array<any>) => any,
+    day: (...args: Array<any>) => any,
+    dayPeriod: (...args: Array<any>) => any,
+  },
+  formatLong?: {
+    date: (...args: Array<any>) => any,
+    time: (...args: Array<any>) => any,
+    dateTime: (...args: Array<any>) => any,
+  },
+  match?: {
+    ordinalNumber: (...args: Array<any>) => any,
+    era: (...args: Array<any>) => any,
+    quarter: (...args: Array<any>) => any,
+    month: (...args: Array<any>) => any,
+    day: (...args: Array<any>) => any,
+    dayPeriod: (...args: Array<any>) => any,
+  },
+  options?: {
+    weekStartsOn?: 0 | 1 | 2 | 3 | 4 | 5 | 6,
+    firstWeekContainsDate?: 1 | 2 | 3 | 4 | 5 | 6 | 7,
+  },
+}
+
+export type Duration = {
+  years?: number,
+  months?: number,
+  weeks?: number,
+  days?: number,
+  hours?: number,
+  minutes?: number,
+  seconds?: number,
+}
+
+export type Day = 0 | 1 | 2 | 3 | 4 | 5 | 6
+
+declare module.exports: (year: number, month: number, day: number) => boolean

backend/node_modules/date-fns/esm/isExists/package.json

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+{
+  "sideEffects": false,
+  "typings": "../../typings.d.ts"
+}