public Type typeCheck(Type container) throws InnerParseError {
                RecordType record = container.expectRecordType(String.format("cannot index into %s, expected object",
                        container));
                return record.get(key)
                        .orElseThrow(() -> new InnerParseError(
                                String.format("%s does not contain field %s", container, key)));
            }
A {@link FunctionDefinition} for the {@link GetAttr} function.
smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/language/syntax/expressions/functions/GetAttr.java