Only vertices required, edges = NULL:
Singleton graph with zero steps:
( 0 )
Singleton graph with one step:
( 0 1 )
Line graph:
( 0 1 2 3 4 )
Line graph, 10 steps, returns on stuck:
( 0 1 2 3 4 )
Line graph backward:
( 4 3 2 1 0 )
Loop at vertex 0:
( 0 0 0 0 0 )
Checking an actual random walk with seed 42:
( 4 2 11 16 19 )

Both vertices and edges required:
Singleton graph with zero steps:
( 0 )
Singleton graph with one step:
( 0 1 )
Line graph:
( 0 1 2 3 4 )
Line graph, 10 steps, returns on stuck:
( 0 1 2 3 4 )
Line graph backward:
( 4 3 2 1 0 )
Loop at vertex 0:
( 0 0 0 0 0 )
Checking an actual random walk with seed 42:
( 4 2 11 16 19 )

Only edges required, vertices = NULL:
Checking error handling:

Only vertices required, edges = NULL:
unweighted directed line graph, 10 steps, errors on stuck.
Vertex out of range.
Negative number of steps.

Both vertices and edges required:
unweighted directed line graph, 10 steps, errors on stuck.
