
If you study the blow notes you see every 3 notes are the Gchord
if you study the draw notes then I geuss you can find some other chords
sometimes they use more holes then one,,what I !! know (told) a bout the harmonica is to serve the chords in the song and for some experiment in sound you blow or draw with some use of syllables such as Oh Oo or weeeeiiii(just as a example) you can invent your own sound or such...bending the notes is a blast..
for me I practice the harmonica not so much but I should 'cos it is such great instrument..