"A setter declaration represents the assign block of a [[ValueDeclaration]]."​
​shared sealed interface SetterDeclaration​
        satisfies NestableDeclaration {
​
    "The variable value this setter is for."​
    shared formal ValueDeclaration variable;
​
    actual => variable.actual;
    
    formal => variable.formal;
​
    default => variable.default;
    
    shared => variable.shared;
​
    containingPackage => variable.containingPackage;
    
    containingModule => variable.containingModule;
    
    container => variable.container;
​
    toplevel => variable.toplevel;
}
​