a.rb

nodes = "" 
# for each node on the list tl
tl.each do |n|
	nodes << n.to_s << ',' 
end
if nodes.size > 0
	nodes = nodes[0, nodes.length - 1]
end
# add the string into the main "timeline" string
timelines << %Q({"time":"#{t}","nodes":[") << nodes << %Q(]"},"

b.rb

nodes = ""
# for each node on the list tl
tl.each do |n|
	nodes = nodes + n.to_s + ','
end
if nodes.size > 0
	nodes = nodes[0, nodes.length - 1]
end
# add the string into the main "timeline" string
timelines = timelines + '{"time":' + t.to_s + ',"nodes":[' + nodes + ']},'