This trait is used to convert a redis value into a more appropriate
type. While a redis Value can represent any response that comes
back from the redis server, usually you want to map this into something
that works better in rust. For instance you might want to convert the
return value into a String or an integer.
Used to convert a value into one or multiple redis argument
strings. Most values will produce exactly one item but in
some cases it might make sense to produce more than one.