<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def calc_freefree_snu_ujy(ne, t, width, elongation, dist, ghz):
 """Calculate a flux density from pure free-free emission. """

    hz = ghz * 1e9
    eta = calc_freefree_eta(ne, t, hz)
    kappa = calc_freefree_kappa(ne, t, hz)
    snu = calc_snu(eta, kappa, width, elongation, dist)
    ujy = snu * cgs.jypercgs * 1e6
    return ujy