The pipe operator
| can be used on to generate a 50/50% choice operation between two tokens. You can also chain them:
1|2|3|4. The behavior of chaining multiple choice operators has not been clearly defined. The distribution might not be the one you expect.
@swim def choosing stuff(p=0.5, i=0): D('bd|pluck', speed='1|2', i=i) again(choosing_stuff, p=0.5, i=i+1)