Ensure the application requirements are all available and ready to be
        packaged as well.

def check_application_requirements(self):
        '''Ensure the application requirements are all available and ready to be
        packaged as well.
        '''
        requirements = self.config.getlist('app', 'requirements', '')
        target_available_packages = self.target.get_available_packages()
        if target_available_packages is True:
            # target handles all packages!
            return

        # remove all the requirements that the target can compile
        onlyname = lambda x: x.split('==')[0]  # noqa: E731
        requirements = [x for x in requirements if onlyname(x) not in
                        target_available_packages]

        if requirements and hasattr(sys, 'real_prefix'):
            e = self.error
            e('virtualenv is needed to install pure-Python modules, but')
            e('virtualenv does not support nesting, and you are running')
            e('buildozer in one. Please run buildozer outside of a')
            e('virtualenv instead.')
            exit(1)

        # did we already installed the libs ?
        if (
            exists(self.applibs_dir) and
            self.state.get('cache.applibs', '') == requirements
        ):
            self.debug('Application requirements already installed, pass')
            return

        # recreate applibs
        self.rmdir(self.applibs_dir)
        self.mkdir(self.applibs_dir)

        # ok now check the availability of all requirements
        for requirement in requirements:
            self._install_application_requirement(requirement)

        # everything goes as expected, save this state!
        self.state['cache.applibs'] = requirements