@Override
            public Type typeCheck(Type container) throws InnerParseError {
                ArrayType arr = container.expectArrayType();
                return Type.optionalType(arr.getMember());
            }
A {@link FunctionDefinition} for the {@link GetAttr} function.
smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/language/syntax/expressions/functions/GetAttr.java