def square_root(number):
	if number < 0 :
		raise Exception("Cannot find the square root of negetive number")
	root = 1
	while(root**2 <= number):
		root += 1
	return root-1

def square_root_test():
	# read assert syntax
	assert 2 == square_root(4)
	assert 4 == square_root(17)
	try:
		square_root(-20)
	except Exeption as e:
		pass
	else:
		assert False