docstr: This seems to be used to pre-fetch assets.
  I don't think that we need this for live-trading.
  Leaving the list empty.
code: def sids(self):
      """
      This seems to be used to pre-fetch assets.
      I don't think that we need this for live-trading.
      Leaving the list empty.
      """
      all_sids = []
      for exchange_name in self.exchanges:
          # This is what initializes each exchanges at the beginning
          # of an algo
          exchange = self.exchanges[exchange_name]
          exchange.init()
  
          all_sids += [asset.sid for asset in exchange.assets]
  
      sids = list(set(all_sids))
      return sids
  
file_path: catalyst/catalyst/exchange/exchange_asset_finder.py
imports: import pandas
  from catalyst.constants import LOG_LEVEL
  from catalyst.exchange.utils.factory import find_exchanges
  from logbook import Logger
label_desc: Use image node_id 2 for calling the ExchangeAssetFinder obj's underlying member method code with example usage: obj.sids() and returns: sids