def check_prerequisites(self):
        """
        Validate the prerequisites required to use the Amazon S3 cache backend.

        Makes sure the Amazon S3 cache backend is configured
        (:attr:`.Config.s3_cache_bucket` is defined by the user) and
        :mod:`boto` is available for use.

        :raises: :exc:`.CacheBackendDisabledError` when a prerequisite fails.
        """
        if not self.config.s3_cache_bucket:
            raise CacheBackendDisabledError("""
                To use Amazon S3 as a cache you have to set the environment
                variable $PIP_ACCEL_S3_BUCKET and configure your Amazon S3 API
                credentials (see the documentation for details).
            """)
        try:
            __import__('boto')
        except __HOLE__:
            raise CacheBackendDisabledError("""
                Boto is required to use Amazon S3 as a cache but it looks like
                Boto is not installed! You can resolve this issue by installing
                pip-accel using the command `pip install pip-accel[s3]'. The
                Amazon S3 cache backend will be disabled for now.
            """)
dataset/ETHPy150Open paylogic/pip-accel/pip_accel/caches/s3.py/S3CacheBackend.check_prerequisites