*   Fixes vulnerabilities arising from incomplete validation in MKL
    requantization
    ([CVE-2021-37665](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-37665))
*   Fixes an undefined behavior arising from reference binding to nullptr in
    `RaggedTensorToVariant`
    ([CVE-2021-37666](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-37666))
*   Fixes an undefined behavior arising from reference binding to nullptr in

      raising an error and quitting.

  Returns:
    [String] The value of var_name after querying for input.

  Raises:
    UserInputError: if a query has been attempted n_ask_attempts times without
      success, assume that the user has made a scripting error, and will
      continue to provide invalid input. Raise the error to avoid infinitely
      looping.
  """