import { isSingletonField } from "https://deno.land/x/http_utils@1.0.0-beta.4/mod.ts";
Weather the field is singleton field or not.
import { isSingletonField } from "https://deno.land/x/http_utils@$VERSION/mod.ts";
import { assertEquals } from "https://deno.land/std@$VERSION/testing/asserts.ts";
assertEquals(isSingletonField("Origin"), true);
assertEquals(isSingletonField("Vary"), false);