Example code of MCMC on somatic variant calling (site specific error model)

Question

[CY]

Some advanced somatic variant calling algorithms use MCMC (something like High-intensity sequencing reveals the sources of plasma circulating cell-free DNA variants). I have already comprehend the statistical logic behind it after some learning process. I still need an example code to get an idea of the actual implementation. However, I can't find a suitable reference code anywhere. Can anyone share some guidance on this. Really appreciated.