Not sure what you're referring to because there is no "union" method/function. There is currently no non-symbolic built-in way to combine dictionaries in an exp

Not sure what you're referring to because there is no "union" method/function. There is currently no non-symbolic built-in way to combine dictionaries in an expression. You may be interested to read PEP 584's list of examples of all the real-world code the existence of this operator makes clearer: https://www.python.org/dev/peps/pep-0584/#examples https://www.python.org/dev/peps/pep-0584/#examples