def create_instance(self, instance_id, configuration_name, node_count,
                        display_name, project_id=None):
        """
        Creates a new Cloud Spanner instance.

        :param instance_id: The ID of the Cloud Spanner instance.
        :type instance_id: str
        :param configuration_name: The name of the instance configuration defining how the
            instance will be created. Possible configuration values can be retrieved via
            https://cloud.google.com/spanner/docs/reference/rest/v1/projects.instanceConfigs/list
        :type configuration_name: str
        :param node_count: (Optional) The number of nodes allocated to the Cloud Spanner
            instance.
        :type node_count: int
        :param display_name: (Optional) The display name for the instance in the GCP
            Console. Must be between 4 and 30 characters.  If this value is not set in
            the constructor, the name falls back to the instance ID.
        :type display_name: str
        :param project_id: Optional, the ID of the  GCP project that owns the Cloud Spanner
            database. If set to None or missing, the default project_id from the GCP connection is used.
        :type project_id: str
        :return: None
        """
        self._apply_to_instance(project_id, instance_id, configuration_name,
                                node_count, display_name, lambda x: x.create())
Creates a new Cloud Spanner instance.

        :param instance_id: The ID of the Cloud Spanner instance.
        :type instance_id: str
        :param configuration_name: The name of the instance configuration defining how the
            instance will be created. Possible configuration values can be retrieved via
            https://cloud.google.com/spanner/docs/reference/rest/v1/projects.instanceConfigs/list
        :type configuration_name: str
        :param node_count: (Optional) The number of nodes allocated to the Cloud Spanner
            instance.
        :type node_count: int
        :param display_name: (Optional) The display name for the instance in the GCP
            Console. Must be between 4 and 30 characters.  If this value is not set in
            the constructor, the name falls back to the instance ID.
        :type display_name: str
        :param project_id: Optional, the ID of the  GCP project that owns the Cloud Spanner
            database. If set to None or missing, the default project_id from the GCP connection is used.
        :type project_id: str
        :return: None