`range` feature suggestion for persistent graph

Since the at function on a persistent graph returns all active edges which were created before and deleted after a reference point (i.e. without a window) it might be nice to have a range function to complement the expanding and rolling. It might look something like

G = rp.PersistentGraph()

# insert some code adding and deleting edges...

# just specified by step size
for view in G.range(step="1 day"):
   # do some graphy thing

# with a start and end point
for view in G.range(start=G.earliest_time, step="1 day", end = G.latest_time):
   # do some graphy thing

but would be equivalent to

times = [ G.earliest_date_time + i*dt.timedelta("1 day") for i in range( some_number ) ]

for t in times:
   G_view = G.at(t)
   # do some graphy thing

Start by locating the PersistentGraph APIs for at, expanding, and rolling, and read how they produce graph views over time. Define the range behavior for step, start, and end, then ensure it yields views equivalent to repeatedly calling at across the requested time points.