code: def get_forwarding_address(destination_address, api_key, callback_url=None, coin_symbol='btc'):
      
      assert api_key, 'api_key required'
  
      resp_dict = get_forwarding_address_details(
              destination_address=destination_address,
              api_key=api_key,
              callback_url=callback_url,
              coin_symbol=coin_symbol
              )
  
      return resp_dict['input_address']
docs: Give a destination address and return an input address that will
      automatically forward to the destination address. See
      get_forwarding_address_details if you also need the forwarding address ID.
  
      Note: a blockcypher api_key is required for this method