Running out of problems

[foreversue]

$ yarn install
yarn install v1.12.3
warning package-lock.json found. Your project contains lock files generated by tools ot
her than Yarn. It is advised not to mix package managers in order to avoid resolution i
nconsistencies caused by unsynchronized lock files. To clear this warning, remove packa
ge-lock.json.
[1/4] Resolving packages...
success Already up-to-date.
Done in 0.39s.

su@DESKTOP-TKN9GJR MINGW64 ~/LanguageServices-WebIDE (master)
$ yarn prepare:env
yarn run v1.12.3
$ ./node_modules/.bin/gulp download-java-server && ./node_modules/.bin/gulp install-py-
server
[13:37:39] Using gulpfile ~\LanguageServices-WebIDE\gulpfile.js
[13:37:39] Starting 'download-java-server'...
jdt-language-server is existed.
[13:37:41] Finished 'download-java-server' after 2.82 s
[13:37:42] Using gulpfile ~\LanguageServices-WebIDE\gulpfile.js
[13:37:42] Starting 'install-py-server'...
[13:37:42] Finished 'install-py-server' after 8.1 ms
'pip' is not recognized as an internal or external command,
operable program or batch file.
child_process.js:651
throw err;
^

Error: Command failed: pip install -i https://pypi.tuna.tsinghua.edu.cn/simple 'python-
language-server[all]'
at checkExecSyncError (child_process.js:611:11)
at Object.execSync (child_process.js:648:13)
at cp.exec (C:\Users\su\LanguageServices-WebIDE\gulpfile.js:26:10)
at ChildProcess.exithandler (child_process.js:296:5)
at ChildProcess.emit (events.js:182:13)
at maybeClose (internal/child_process.js:962:16)
at Socket.stream.socket.on (internal/child_process.js:381:11)
at Socket.emit (events.js:182:13)
at Pipe._handle.close (net.js:606:12)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.