Subsets

def subsets(s):
    """s is a list representing a set;
    the function prints all the subsets of s"""
    myStr = [""]
    myStr1 = [""]
    for i in s:
        for j in myStr:
            myStr1.append(str(j)+str(i))
        myStr = myStr1[:]
    for c in myStr:
        print "{" + str(c) + "}"

subsets(["a","b","c","d"])