Retrieve an item from a dictionary using an arbitrary object as the key

[abcd]

Hi,
    I have a class such as,

class Type:
    def __init__(self, val):
        self.val = val

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

So I have a dictionary which maps an instance of Type to an instance
of Person.  Now I need to retrieve a particular Person given a Type
object.  What method in Type do I need to implement to allow it to be
retrieved?

For example (this is just an example):

t = Type(19)
p = Person("bob", 99)

x = {t : p}

....<later on in the code somewhere>....

def getPerson(val):
    return x[Type(val)]

getPerson(19)  ....should return me the Person with name "bob" and age
99.  I am thinking there is some method that is used by the dictionary
to know if the key exists, just not sure which.

thanks