<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def create_psf(event_class, event_type, dtheta, egy, cth):
 """Create an array of PSF response values versus energy and inclination angle. Parameters egy : `~numpy.ndarray` Energy in MeV. cth : `~numpy.ndarray` Cosine of the incidence angle. """

    irf = create_irf(event_class, event_type)
    theta = np.degrees(np.arccos(cth))
    m = np.zeros((len(dtheta), len(egy), len(cth)))

    for i, x in enumerate(egy):
        for j, y in enumerate(theta):
            m[:, i, j] = irf.psf().value(dtheta, x, y, 0.0)

    return m