def findMinAndMax(L):

if isinstance(L,list) ==False:
    return (None,None)
elif len(L)== 0:
    return (None,None)
else :
        Max = L[0]
        Min = L[0]
        for i in L:
            if Max <i:
                Max = i 
            if Min >i:
                Min = i
        return (Min,Max)