Which keyword or operator is used to see if two variables share a single memory space? 0000 in is square

The keyword used to check if two variables share a single memory space in Python is `is`. In Python, the `is` operator is used to compare the memory locations of two objects. If two variables share the same memory location, the `is` operator will return `True`. Here is an example:<br /><br />```python<br />a = 5<br />b = 5<br />print(a is b) # Output: True<br />```<br /><br />In this example, both `a` and `b` are assigned the value `5`, and the `is` operator is used to check if they share the same memory location. Since they do refer to the same memory location, the output is `True`.<br /><br />The other options provided (`0000`, `in`, and `$\square $`) are not relevant to checking if two variables share a single memory space.