def clean_builds(self, _args):
        """Delete all build caches for each recipe, python-install, java code
        and compiled libs collection.

        This does *not* delete the package download cache or the final
        distributions.  You can also use clean_recipe_build to delete the build
        of a specific recipe.
        """
        ctx = self.ctx
        if exists(ctx.build_dir):
            shutil.rmtree(ctx.build_dir)
        if exists(ctx.python_installs_dir):
            shutil.rmtree(ctx.python_installs_dir)
        libs_dir = join(self.ctx.build_dir, 'libs_collections')
        if exists(libs_dir):
            shutil.rmtree(libs_dir)