Return a fully-qualified any_path string.

def any_path_path(cls, project, database, document, any_path):
        """Return a fully-qualified any_path string."""
        return google.api_core.path_template.expand(
            "projects/{project}/databases/{database}/documents/{document}/{any_path=**}",
            project=project,
            database=database,
            document=document,
            any_path=any_path,
        )