If you come across an expression that is hard to understand or it is duplicated in several places throughout you code, the Extract Variable refactoring can help you deal with those problems placing the result of such expression or its part into a separate variable that is less complex and easier to understand. Plus, it reduces the code duplication.
In the editor, select an expression or its part that you want to extract. You can also position the caret within the expression, in this case GoLand offers you a list of potential code selections.
Press Ctrl+Alt+V or from the main menu, select.
Select a name suggested in the popup or type your own and press Enter. If GoLand finds more than one occurrence, it lets you specify whether or not you want to extract this variable for all of them.