private Object getPositionalArgument(int index) {
            if (index >= arguments.length) {
                throw error(String.format("Given %d arguments but attempted to format index %d",
                        arguments.length,
                        index));
            } else {
                // Track the usage of the positional argument.
                positionals[index] = true;
                return arguments[index];
            }
        }
A BlockOperation that repeats a template for each value referenced by the block. Each iteration pushes
a state to the writer that includes key, value, key.first, and key.last context properties. The name
of the context property can be customized in the template.
smithy-utils/src/main/java/software/amazon/smithy/utils/CodeFormatter.java