Write the function intersection
that takes two dictionaries and returns another dictionary containing the intersection of two dictionaries. An empty dictionary should be return if two input dictionaries do not have any intersection. Both the key and value should be the same in input dictionaries to be considered in the intersection.
a = {'name': 'Dave', 'age': 25, 'gender': 'male'}
b = {'name': 'Sarah', 'age': 25, 'gender': 'female', 'bmi': 20}
intersection(a, b) -> {'age': 25}