intset.py

class intSet(object):
    """
    An intSet is a set of integers
    The value is represented by a list of ints, self.vales.
    Each int in the set occurs in self.vals exactly once.
    """

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

    def insert(self, e):
        """Assumes e is an integers 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 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 __str__(self):
        self.vals.sort()
        return '{' + ','.join([str(e) for e in self.vals]) + '}'