code: def upgrade_packages(self, packages):
          
  
          print("Upgrading packages\n")
  
          package_list = []
          requirements = self._parse_requirements(packages.readlines())
          for (package, version) in requirements:
              package_list.append(package)
  
          if package_list:
              args = [
                  "pip",
                  "install",
                  "-U",
              ]
              args.extend(package_list)
              subprocess.check_call(args)
          else:
              print("No packages to upgrade")
docs: Upgrade all specified packages to latest version