Assertion: accordion | /r/Desires | 4 buttons
Facets:
value: to produce the same notes
type: PURPOSE
Source sentences:
text: (Another way to understand this difference is to consider the fact that a double-action instrument generally requires twice as many keys or buttons to produce a range of notes as a single-action instrument: for example, a piano accordion requires 8 keys (16 reeds) to sound a diatonic scale from C to C', where a DBA pitched in C requires 4 buttons (8 reeds) to produce the same notes.)