<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def plot_pyro(calc_id=-1):
 """ Plot the pyroclastic cloud and the assets """

    # NB: matplotlib is imported inside since it is a costly import
    import matplotlib.pyplot as p
    dstore = util.read(calc_id)
    sitecol = dstore['sitecol']
    asset_risk = dstore['asset_risk'].value
    pyro, = numpy.where(dstore['multi_peril']['PYRO'] == 1)
    lons = sitecol.lons[pyro]
    lats = sitecol.lats[pyro]
    p.scatter(lons, lats, marker='o', color='red')

    building_pyro, = numpy.where(asset_risk['building-PYRO'] == 1)
    lons = sitecol.lons[building_pyro]
    lats = sitecol.lats[building_pyro]
    p.scatter(lons, lats, marker='.', color='green')
    p.show()