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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 validate_currency(*currencies):
 	""" some validation checks before doing anything """

	validated_currency = []
	if not currencies:
		raise CurrencyException('My function need something to run, duh')
	for currency in currencies:
		currency = currency.upper()
		if not isinstance(currency, str):
			raise TypeError('Currency code should be a string: ' + repr(currency))
		if currency not in _currencies:
			raise CurrencyException('Currency code not found: ' + repr(currency))
		validated_currency.append(currency)
	return validated_currency[0] if len(validated_currency) == 1 else validated_currency