command:        mbs 3 -t 0.001 -r 0.00025 -s 5000 2500 -f 1 1 traj 

//0-1   allele: a a a d d d d 
segsites: 7
positions: 79.1001 80.1001 81.101 82.101 83.10001 84.801 85
1111111
5555555
4444444