s either a D flat
or C sharp for the second note. This pitch does not occur (except as an
accidental) in either of those keys.</p>
<p>Nevertheless, because F is a key with some number of sharps and G is
a key with some number of flats, transpositions resulting in any
non-natural notes are represented as flats and sharps, respectively. The
key of C major and its relative A minor have only natural notes. Setting
<code>key "c"</code> or <code>key = "am"</code> results in the default
behavior, falling back on s