Two Sum III - Data structure design

Design and implement a TwoSum class. It should support the following operations:addandfind.

add- Add the number to an internal data structure. find- Find if there exists any pair of numbers which sum is equal to the value.

For example,

add(1); add(3); add(5);
find(4) -> true
find(7) -> false

class TwoSum(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.table = dict()


    def add(self, number):
        """
        Add the number to an internal data structure..
        :type number: int
        :rtype: void
        """
        if not self.table.has_key(number):
                self.table[number] = 1
        else:
                self.table[number] += 1

    def find(self, value):
        """
        Find if there exists any pair of numbers which sum is equal to the value.
        :type value: int
        :rtype: bool
        """
        for k in self.table.keys():
                if k == (value - k) and self.table[k] > 1:
                    return True
                elif k != (value - k) and self.table.has_key(value - k):
                    return True
        return False