private fun getExpectedTypeOfElvisOperand(expression: PsiElement): KtType? {
        val binaryExpression = expression.unwrapQualified<KtBinaryExpression> { binaryExpression, operand ->
            binaryExpression.operationToken == KtTokens.ELVIS && (operand == binaryExpression.left || operand == binaryExpression.right)
        } ?: return null
        if (expression !is KtExpression) return null

            // Binary expressions with type RHS always use its operand.
            is KtBinaryExpressionWithTypeRHS ->
                parent.left == child

            // Is expressions always use their LHS.
            is KtIsExpression ->
                parent.leftHandSide == child

            // Unary expressions always use its operand.
            is KtUnaryExpression ->