



def   UpperCAmelCase							(		A__     )							->					str:






	if not isinstance(A__				,  A__     ):
		raise ValueError("""double_factorial() only accepts integral values"""     )
	if n < 0:
		raise ValueError("""double_factorial() not defined for negative values"""     )
	return 1 if n <= 1 else n * double_factorial(n - 2     )


if __name__ == "__main__":
						import doctest

						doctest.testmod()








"""simple docstring"""





def 							_lowerCAmelCase   (    UpperCAmelCase  :				int					):


					'''simple docstring'''






					if not isinstance(UpperCAmelCase   ,				UpperCAmelCase					):
										raise ValueError('''double_factorial() only accepts integral values'''					)
					if n < 0:
										raise ValueError('''double_factorial() not defined for negative values'''					)
					return 1 if n <= 1 else n * double_factorial(n - 2					)


if __name__ == "__main__":
				import doctest

				doctest.testmod()


