[Destructively] modifies the item specified by the
indexes to the value.
item-at! < > < t > |
item-at! < array > < t > |
item-at! < > < t > |
item-at! < > < t > |
item-at! < > < t > |
item-at! :before < > < t > |
item-at! :around < > < t > |
item-at! < > < t > |
item-at! < > < t > |
item-at! < > < t > |
item-at! < > < t > |
item-at! < t > < hash-table > |
item-at! < > < t > |