# Check for custom objects in Python set.
Python set data structure is commonly used for removing duplicate entriesand make lookup faster (O(1)). Any hashable object can be stored in set.For example, `` list `` and `` dict `` can’t be stored.

User defined objects can be stored. Here is how it looks.

    class Person(object):
        def __init__(self, name, age):
            self.name, self.age = name, age


    In [25]: s = set()
    In [26]: s.add(Person('kracekumar', 25))

    In [27]: s
    Out[27]: set([<__main__.Person at 0x1033c5e10>])

    In [29]: Person('kracekumar', 25) in s
    Out[29]: False

### Implement equality check

Even though `` Person `` object with same value is present but check failed.This is because default python `` __eq__ `` checks for reference.

    class Person(object):
        def __init__(self, name, age):
            self.name, self.age = name, age

        def __eq__(self, other):
            return (isinstance(other, self.__class__) and
                getattr(other, 'name', None) == self.name and
                getattr(other, 'age', None) == self.age)

        def __hash__(self):
            return hash(self.name + str(self.age))

    In [38]: s = set()

    In [39]: s.add(Person('kracekumar', 25))

    In [40]: Person('kracekumar', 25) in s
    Out[40]: True

    In [41]: s
    Out[41]: set([<__main__.Person at 0x1033d0590>])

    In [42]: s.add(Person('kracekumar', 25))

    In [43]: s
    Out[43]: set([<__main__.Person at 0x1033d0590>])

`` __hash__ `` is used for calculating hash of the object and `` __eq__ `` is used by`` in `` during check after hash value match.