class IntSet(object):
    def __init__(self):
        """Create an empty set of integers"""
        self.vals = []

    def insert(self, e):
        """Assumes e is an integer and inserts e into self"""
        if not e in self.vals:
            self.vals.append(e)

    def member(self, e):
        """
        Assumes e is an integer
        Returns True if e is in self, and False otherwise"""
        return e in self.vals

    def remove(self, e):
        """
        Assumes e is an integer and removes e from self
        Raises ValueError if e is not in self"""
        try:
            self.vals.remove(e)
        except:
            raise ValueError(str(e) + 'not found')

    def getMembers(self):
        """Returns a list containing the elements of self.
        Nothing can be assumed about the order of the elements"""
        return self.vals[:]

    def __str__(self):
        """Returns a string representation of self"""
        self.vals.sort()
        result = ''
        for e in self.vals:
            result = result + str(e) + ','
        return '{' + result[:-1] + '}' #-1 omits trailing comma
@@ -958,32 +958,33 @@
 .sort()%0A        
+#
 result = ''%0A    
@@ -987,16 +987,17 @@
         
+#
 for e in
@@ -1012,24 +1012,25 @@
 ls:%0A        
+#
     result =
@@ -1056,24 +1056,25 @@
 ','%0A        
+#
 return '%7B' +
@@ -1116,8 +1116,100 @@
 ng comma
+%0A        # or you could use%0A        return '%7B' + ','.join(%5Bstr(e) for e in self.vals%5D) + '%7D'

add another way of implementation of __str__()