def extract_node_variable(self, part: str) -> Optional[str]:
        """
        Extract node variable.

        Args:
            part: node in string format

        """
        part = part.lstrip("(").rstrip(")")
        idx = part.find(":")
        if idx != -1:
            part = part[:idx]
        return None if part == "" else part

        Extract node variable.

        Args:
            part: node in string format

        
llama-index-integrations/graph_stores/llama-index-graph-stores-neo4j/llama_index/graph_stores/neo4j/cypher_corrector.py