def get_sequence_frequencies(sequences):
	"""
	Computes the frequencies of different sequences in a collection, returning a dictionary of their string representations and counts.
	
	Example
	--------
	>>> s1 = [1,1,2,2,3]
	>>> s2 = [1,2,2,3,3]
	>>> s3 = [1,1,2,2,2]
	>>> sequences = [s1,s2,s2,s3,s3,s3]
	>>> ps.get_sequence_frequencies(sequences) #doctest: +NORMALIZE_WHITESPACE
	{'[1, 1, 2, 2, 2]': 3, 
	 '[1, 2, 2, 3, 3]': 2, 
	 '[1, 1, 2, 2, 3]': 1}
	"""
	
	# converting to strings makes comparison easy
	sequences_as_strings = [str(s) for s in sequences]
	
	sequence_frequencies = {}
	for sequence in set(sequences_as_strings):
		sequence_frequencies[sequence] = sequences_as_strings.count(sequence)
	
	sequence_frequencies = {k: v for k, v in sorted(sequence_frequencies.items(), key=lambda item: item[1], reverse=True)}
	
	return sequence_frequencies