code: def sign_transaction(self, tx):
      url = "https://legacy.mycrypto.com/#offline-transaction"
      print(
          "\nVisit {url} and enter the following parameters:\n\n"
          "From Address:\t\t{_from}\n"
          '\n\tClick the "Generate Information" button\n\n'
          "To Address:\t\t{to}\n"
          "Value / Amount to Send:\t{value}\n"
          "Gas Limit:\t\t{gas}\n"
          "Gas Price:\t\t[Accept the default value]\n"
          "Nonce:\t\t\t{nonce}\n"
          "Data:\t\t\t{data}\n".format(
              url=url,
              _from=tx["from"],
              to=tx["to"],
              value=tx["value"],
              gas=tx["gas"],
              nonce=tx["nonce"],
              data=tx["data"],
          )
      )
  
      webbrowser.open_new(url)
  
      signed_tx = input(
          'Copy and Paste the "Signed Transaction" ' "field here:\n"
      )
  
      if signed_tx.startswith("0x"):
          signed_tx = signed_tx[2:]
  
      return signed_tx
  
imports: from __future__ import print_function
  import glob
  import json
  import os
  import re
  import shutil
  import sys
  import time
  import webbrowser
  import bcolz
  import logbook
  import pandas
  import requests
  from requests_toolbelt import MultipartDecoder
  from requests_toolbelt.multipart.decoder import NonMultipartContentTypeException
  from catalyst.constants import LOG_LEVEL, AUTH_SERVER, ETH_REMOTE_NODE, MARKETPLACE_CONTRACT, MARKETPLACE_CONTRACT_ABI, ENIGMA_CONTRACT, ENIGMA_CONTRACT_ABI, TERMS_AND_CONDITIONS
  from catalyst.exchange.utils.stats_utils import set_print_settings
  from catalyst.marketplace.marketplace_errors import MarketplaceDatasetNotFound, MarketplaceNoAddressMatch, MarketplaceHTTPRequest, MarketplaceNoCSVFiles, MarketplaceRequiresPython3
  from catalyst.marketplace.utils.auth_utils import get_key_secret, get_signed_headers
  from catalyst.marketplace.utils.eth_utils import bin_hex, from_grains, to_grains
  from catalyst.marketplace.utils.path_utils import get_bundle_folder, get_data_source_folder, get_marketplace_folder, get_user_pubaddr, get_temp_bundles_folder, extract_bundle, save_user_pubaddr
  from catalyst.utils.paths import ensure_directory
label_desc: Use image node_id 4 for calling the Marketplace obj's underlying member method code with example usage: obj.sign_transaction(tx) and returns: signed_tx