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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 getTheme(theme=None):
 	""" 	Returns a theme definition. 	To see the colors translated (hex) use 	cufflinks.getLayout(theme) instead. 	"""

	if not theme:
		theme = auth.get_config_file()['theme']

	if theme in THEMES:
		return updateColors(copy.deepcopy(THEMES[theme]))
	else:
		raise Exception("Invalid Theme: {0}".format(theme))