When I Run indexing.py file with the terminal This is Code indexing.py from langchain.document_loaders import DirectoryLoader from langchain.text_splitter import RecursiveCharacterTextSplitter import os directory = '/data/SwiftProgrammingLanguage.pdf' def load_docs(directory): loader = DirectoryLoader(directory) documents = loader.load() return documents documents = load_docs(directory) len(documents) def split_docs(documents,chunk_size=500,chunk_overlap=20): text_splitter = RecursiveCharacterTextSplitter(chunk_size=chunk_size, chunk_overlap=chunk_overlap) docs = text_splitter.split_documents(documents) return docs docs = split_docs(documents) print(len(docs)) **when I run python3 indexing.py Getting error python3 indexing.py /Users/sarit.bahuguna/ai_chatbot/data/SwiftProgrammingLanguage.pdf [nltk_data] Error loading punkt: <urlopen error [Errno 60] Operation