Watch the Western Swing Lead 2 online guitar lesson by Joe Dalton from 50 Country Guitar Licks You MUST Know
Adding a chromatic line to your bag of licks and tricks gives you a melodic choice to break things up a bit. This way we can avoid always sounding pentatonic or diatonic (fancy word for the major scale). The beginning of the lick features the chromatic run (the half steps). Then we have an arpeggio (single notes from the chord). Some of the coolness of the lick comes from combining these two features.