This function is run inside the weirdo casapy IPython environment! A
    strange set of modules is available, and the
    `pwkit.environments.casa.scripting` system sets up a very particular
    environment to allow encapsulated scripting.

def in_casapy (helper, vis=None, figfile=None):
    """This function is run inside the weirdo casapy IPython environment! A
    strange set of modules is available, and the
    `pwkit.environments.casa.scripting` system sets up a very particular
    environment to allow encapsulated scripting.

    """
    if vis is None:
        raise ValueError ('vis')

    helper.casans.plotants (vis=vis, figfile=figfile)