How to write sdc for pre/post CTS ?

I want to set different clock uncertainity values in the same sdc file for both pre and post CTS modes. Can I do that ? The following sdc didn't work. How to do that ?

if {[getAnalysisMode -clockPropagation -quiet] == "forcedIdeal"} {
    set jit_add 0.2
} else {
    set jit_add 0
}
set_clock_uncertainty [expr 0.200+${jit_add}] \
  -from [get_clocks {my_clk}] -to [get_clocks {my_clk}]