Returns a new container C (of the same type as a)
such that C contains every entry in a and b. C may share structure witha and b.
| merge-entries < iteratable-container-mixin > < iteratable-container-mixin > |
| merge-entries < key-value-iteratable-container-mixin > < key-value-iteratable-container-mixin > |
| merge-entries < list > < list > |
| merge-entries < list > < t > |
| merge-entries < null > < iteratable-container-mixin > |
| merge-entries < null > < key-value-iteratable-container-mixin > |
| merge-entries < null > < t > |
| merge-entries < t > < t > |
| merge-entries :around < t > < t > |