code: def download_exchange_symbols(exchange_name):
      """
      Downloads the exchange's symbols.json from the repository.
  
      Parameters
      ----------
      exchange_name: str
      environ:
  
      Returns
      -------
      str
  
      """
      filename = get_exchange_symbols_filename(exchange_name)
      url = SYMBOLS_URL.format(exchange=exchange_name)
      response = request.urlretrieve(url=url, filename=filename)
      return response
  
imports: import hashlib
  import json
  import os
  import pickle
  import shutil
  from datetime import date, datetime
  import pandas
  from catalyst.assets._assets import TradingPair
  from six import string_types
  from six.moves.urllib import request
  from catalyst.constants import DATE_FORMAT, SYMBOLS_URL
  from catalyst.exchange.exchange_errors import ExchangeSymbolsNotFound
  from catalyst.exchange.utils.serialization_utils import ExchangeJSONEncoder, ExchangeJSONDecoder
  from catalyst.utils.memoize import weak_lru_cache
  from catalyst.utils.paths import data_root, ensure_directory, last_modified_time
label_desc: Use image node_id 6 for calling a global function with example usage: download_exchange_symbols(exchange_name) and returns: response