+-------------------------------------------------------------------+
|  Picker:find()--------------------+    +------>Picker             |
|   |        ^                      |    |                          |
|   |        |                      v    |                          |
|   |  +----------------+   +----------------+                      |
|   +->|     Finder     +   |     Sorter     |                      |
|      +----------------+   +----------------+                      |
|                   [1]                                             |
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
+-------------------------------------------------------------------+

Picker starts a `finder`.
    Finder returns a list of `entries` to Picker.
    Picker can optionally sort w/ `Sorter`.
    Picker can optionally preview selected with `Previewer`

    Then you can map stuff in the picker to decide what to do next.