هنگام اجرای دستور pyinstaller --onefile -w .\zzzz.py  با این خطای مواجه میشم دلیلش چیه؟؟؟

pyinstaller : The term 'pyinstaller' is not recognized as the name of a cmdlet, function, script file, or operable  

program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.    

At line:1 char:1

+ pyinstaller --onefile -w .\zzzz.py

+ ~~~~~~~~~~~

   + CategoryInfo          : ObjectNotFound: (pyinstaller:String) [], CommandNotFoundException

   + FullyQualifiedErrorId : CommandNotFoundException