How would you use dry-types/dry-schema to map a finite set of possible Strings to
a finite set of Symbols? `Types::String.enum('string' => :symbol)` only seems to map Strings and Symbols to Strings. I need the output to be Symbols.

Input: ['syn', 'ack']
Output: [:syn, :ack]

#dry_rb #dry_types #dry_schema