a=b to create two undirected edges between
a and b.
Use the keyword integrate to compute the integral
from zero to one.
Example
root 1
integrate
1=2
yields the output 0.6666666666666667
sink t to compute the probability that
t is connected to the root.
Example
root 1
sink 3
1-2, 2-3, 3-4, 4-5, 5-6, 6-1
yields the output p^2 + p^4 - p^6