private fun isUsed(psiElement: PsiElement): Boolean {
        return when (psiElement) {
            /**
             * DECLARATIONS
             */
            // Inner PSI of KtLambdaExpressions. Used if the containing KtLambdaExpression is.
            is KtFunctionLiteral ->
                doesParentUseChild(psiElement.parent, psiElement)

            // KtNamedFunction includes `fun() { ... }` lambda syntax. No other