The Most Numbers. Why isnt this solution accepted?

#I get the following errors: 
#TypeError: 'float' object is not iterable, checkio, 2
#Fail: checkio(-0.07)




def checkio(*args):
    if len(args) > 0: x=max(*args)-min(*args)
    else: x=0
    return x

#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
    def almost_equal(checked, correct, significant_digits):
        #print(type(checked))
        precision = 0.1 ** significant_digits
        #print(correct - precision, checked, correct + precision)
        return correct - precision < checked < correct + precision

    print('Example:')
    print(checkio(1, 2, 3))

    assert almost_equal(checkio(1, 2, 3), 2, 3), "3-1=2"
    assert almost_equal(checkio(5, -5), 10, 3), "5-(-5)=10"
    assert almost_equal(checkio(10.2, -2.2, 0, 1.1, 0.5), 12.4, 3), "10.2-(-2.2)=12.4"
    assert almost_equal(checkio(), 0, 3), "Empty"
    print("Coding complete? Click 'Check' to review your tests and earn cool rewards!")