* penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.
   *
   * This implementation uses a per-segment queue to record a memento of the additions, removals,
   * and accesses that were performed on the map. The queue is drained on writes and when it exceeds

FieldName     = identifier .
Element       = Expression | LiteralValue .
</pre>

<p>
The LiteralType's underlying type must be a struct, array, slice, or map type
(the grammar enforces this constraint except when the type is given
as a TypeName).
The types of the elements and keys must be <a href="#Assignability">assignable</a>
to the respective field, element, and key types of the literal type;