divide list ['a', 'b', 'c', '1', '2', '3'] into three separate list

def seperate_list(l):
    l1 = []
    l2 = []
    l3 = []
    for i in l:
        if i.isdigit():
            l1.append(i)
        elif i.isalpha():
            l2.append(i)
        else:
            l3.append(i)
    return l1, l2, l3