Hello Python Ideas,

Currently, to check whether a single key is in a dictionary, we use the "in" keyword. However, there is no built-in support for checking if a key-value pair belongs in a dictionary.

Currently, we presuppose that the object being checked has the same type as that of the key. What if we allowed the "in" operator to accept a tuple that denotes a (mapped) key-value pair?

Let us consider how that might work using the canonical example given in the tutorial:

>>> tel = {'jack': 4098, 'sape': 4139}


>>> ('jack', 4098) in tel
True
>>> ('jack', 4000) in tel
False
>>> 'jack' in tel
True

As you can see, the "in" operator would interpret the object as either a key or a key-value pair depending on the actual types of the object, key and value. In the key itself happens to be a tuple, then the key-value membership test would involve a nested tuple, whose first item is a tuple denoting the key.

Best Regards,
Karthick Sankarachary