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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 is_cached(file_name):
 	""" 	Check if a given file is available in the cache or not 	"""


	gml_file_path = join(join(expanduser('~'), OCTOGRID_DIRECTORY), file_name)

	return isfile(gml_file_path)