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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_base_image_cmd(self, force):
 """ Build the glusterbase image """

        check_permissions()

        basetag = self.conf.basetag
        basedir = self.conf.basedir
        verbose = self.conf.verbose

        if self.image_exists(tag=basetag):
            if not force:
                echo("Image with tag '{0}' already exists".format(basetag))
                return self.image_by_tag(basetag)
            else:
                self.remove_image(basetag)
        echo("Building base image")
        stream = self.build(path=basedir, rm=True, tag=basetag)
        err = self.__handle_build_stream(stream, verbose)
        if err:
            echo("Building base image failed with following error:")
            echo(err)
            return None

        image = self.image_by_tag(basetag)
        echo("Built base image {0} (Id: {1})".format(basetag, image['Id']))
        return image