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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fromfilenames(cls, filenames, coltype=LIGOTimeGPS):
 		""" 		Read Cache objects from the files named and concatenate the results into a 		single Cache. 		"""

		cache = cls()
		for filename in filenames:
			cache.extend(cls.fromfile(open(filename), coltype=coltype))
		return cache