or "true" allows the debug options passed within an XRTCompile op to be
        passed directly to the XLA compilation backend. If such variable is not
        set (service side), only a restricted set will be passed through.
    *   Allow the XRTCompile op to return the ProgramShape resulted form the XLA
        compilation as a second return argument.
    *   XLA HLO graphs can now be rendered as SVG/HTML.
*   Estimator