<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _to_chroma(pianoroll):
 """Return the unnormalized chroma features of a pianoroll."""

    _validate_pianoroll(pianoroll)
    reshaped = pianoroll[:, :120].reshape(-1, 12, 10)
    reshaped[..., :8] += pianoroll[:, 120:].reshape(-1, 1, 8)
    return np.sum(reshaped, 1)