| An *enum* is a FIDL data type that represents a fixed list of possible |
| constants, like the suits in a deck of playing cards, or the make of car a user |
| may select from a dropdown menu. This list of values is then mapped over an |
| underlying integer type, with each value thereof corresponding to one of the |
| listed members. |
| |
| In the example below, a FIDL enum is added in a scenario where enums are a |
| perfect fit: enumerating the possible error values that may be emitted by a |
| failed method call. The `ReadError` enum has two members: `NOT_FOUND` is used to |
| indicate that a search key could not be matched during a read attempt, while |
| `UNKNOWN` serves as a grab-bag error for all cases that cannot be explicitly |
| described. Note that this enum is marked `flexible`, allowing it to be easily |
| evolved with new members in the future. |
| |
| <<../examples/key_value_store/_callout.md>> |
| <<../examples/key_value_store/_add_read_item_tutorial.md>> |
