Modify xformers instead of pytorch

def prepare_environment():

    torch_command = os.environ.get('TORCH_COMMAND', "pip install torch==2.0.1+cu118 torchvision==0.15.2+cu118 --extra-index-url https://download.pytorch.org/whl/cu118")

    torch_index_url = os.environ.get('TORCH_INDEX_URL', "https://download.pytorch.org/whl/cu118")

    torch_command = os.environ.get('TORCH_COMMAND', f"pip install torch==2.0.1 torchvision==0.15.2 --extra-index-url {torch_index_url}")

    requirements_file = os.environ.get('REQS_FILE', "requirements_versions.txt")

    xformers_package = os.environ.get('XFORMERS_PACKAGE', 'xformers==0.0.17')

                if not is_installed("xformers"):

                    exit(0)

        elif platform.system() == "Linux":

            run_pip(f"install {xformers_package}", "xformers")

            run_pip(f"install -U -I --no-deps {xformers_package}", "xformers")

    if not is_installed("pyngrok") and args.ngrok:

        run_pip("install pyngrok", "ngrok")