def noSameEdge(G, sol):
	"""
	The car should never drive along the same directed edge more than once.

	Input:
		G: A NetworkX graph that represents the input problem
		sol: List of edges in the solution path
	Returns:
		Boolean value indicating if the solution enforces this lemma
	"""
	seen = {}
	for edge in sol:
		s, e = edge[0], edge[1]
		if e in seen.get(s, []):
			return False
		else:
			seen[s] = seen.get(s, []) + [e]
	return True