Dominant chords are considered to sound unstable in a classical music harmony context, and so in a classical piece, these chords often resolve down a perfect fifth or up a perfect fourth (e.g. C7 tends to resolve onto chords based on F, such as F major or F minor). However, in a jazz context, particularly in music from the 1940s bebop era and later decades, dominant chords were no longer treated as "unstable" chords. Some bebop tunes use a dominant chord as the tonic chord and also use dominant chords for the chords that would typically be minor chords in a Classical piece or a swing arrangement. For example, while a Classical piece and a swing arrangement might use the following chord sequence in the key of C major: "", a bebop bandleader might reharmonize the same progression as "", making a sequence of dominant seventh chords, so long as the new dominant chord harmonies were compatible with the tune's melody. For more details, see chord progression.