code: def _fetchAzureAccountKey(accountName):
      
      try:
          return os.environ['AZURE_ACCOUNT_KEY_' + accountName]
      except KeyError:
          try:
              return os.environ['AZURE_ACCOUNT_KEY']
          except KeyError:
              configParser = RawConfigParser()
              configParser.read(os.path.expanduser(credential_file_path))
              try:
                  return configParser.get('AzureStorageCredentials', accountName)
              except NoOptionError:
                  raise RuntimeError("No account key found for '%s', please provide it in '%s'" %
                                     (accountName, credential_file_path))
docs: Find the account key for a given Azure storage account.
  
      The account key is taken from the AZURE_ACCOUNT_KEY_<account> environment variable if it
      exists, then from plain AZURE_ACCOUNT_KEY, and then from looking in the file
      ~/.toilAzureCredentials. That file has format:
  
      [AzureStorageCredentials]
      accountName1=ACCOUNTKEY1==
      accountName2=ACCOUNTKEY2==