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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def call_s3guard_prune(credential_name):
 """ Runs S3Guard prune command on external account associated with the given credential_name. """
  # Get the AWS credential account associated with the credential
  account = get_external_account(api, credential_name)
  # Invoke the prune command for the account by its name
  cmd = account.external_account_cmd_by_name('S3GuardPrune')
  print ("Issued '{0}' command with id '{1}'".format(cmd.name, cmd.id))
  print ("Waiting for command {0} to finish...".format(cmd.id))
  cmd = cmd.wait()
  print ("Command succeeded: {0}".format(cmd.success))