How to change a master clock rate on USRP B210

Hello All Gnu Radio user,
To use a 2 TX, I want to change a clock rate to an accepted one, under
30.72 MHz. I use the API with uhd_usrp_probe and it works only for this
command. Can you give me the idea or python code to use this argument
parameter with a python flowgraph?

In the device parameter write ‘set_master_clock_rate=30e6’