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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.import type { ReleaseType, SemVer } from "./types.ts";import { eq } from "./eq.ts";
/** Returns difference between two versions by the release type, or * `undefined` if the versions are the same. */export function difference(  s0: SemVer,  s1: SemVer,): ReleaseType | undefined {  if (eq(s0, s1)) {    return undefined;  } else {    let prefix = "";    let defaultResult: ReleaseType | undefined = undefined;    if (s0 && s1) {      if (s0.prerelease.length || s1.prerelease.length) {        prefix = "pre";        defaultResult = "prerelease";      }
      for (const key in s0) {        if (key === "major" || key === "minor" || key === "patch") {          if (s0[key] !== s1[key]) {            return (prefix + key) as ReleaseType;          }        }      }    }    return defaultResult; // may be undefined  }}