This task does not do a uvdata subtraction (aka Cotton-Schwab major cycle) of model visibility as in clean. - For ALMA Commissioning

    Keyword arguments:
    vis -- Name of input visibility file
            default: none; example: vis='ngc5921.ms'
    imagename -- Name of output CASA image. (only the prefix)
                   default: none; example: imagename='m2'
                   output images are:
                 m2.image; cleaned and restored image
                        With or without primary beam correction
                 m2dirty.image; dirty image
                 m2psf.image; point-spread function (dirty beam)
                 m2.model; image of clean components
                 m2.mask; image containing clean regions, when interative=True
    field -- Select fields in mosaic.  Use field id(s) or field name(s).
                  ['go listobs' to obtain the list id's or names]
              default: ''= all fields
              If field string is a non-negative integer, it is assumed to
                  be a field index otherwise, it is assumed to be a
          field name
              field='0~2'; field ids 0,1,2
              field='0,4,5~7'; field ids 0,4,5,6,7
              field='3C286,3C295'; field named 3C286 and 3C295
              field = '3,4C*'; field id 3, all names starting with 4C
    spw -- Select spectral window/channels
           NOTE: This selects the data passed as the INPUT to mode
           default: ''= all spectral windows and channels
                spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
                spw='0:5~61'; spw 0, channels 5 to 61
                spw='<2';   spectral windows less than 2 (i.e. 0,1)
                spw='0,10,3:3~45'; spw 0,10 all channels, spw 3,
                   channels 3 to 45.
                spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
                spw='0:0~10;15~60'; spectral window 0 with channels
                spw='0:0~10,1:20~30,2:1;2;3'; spw 0, channels 0-10,
                      spw 1, channels 20-30, and spw 2, channels, 1,2 and 3
        advise -- This determines whether advice for imsize and cell is
                  requested. If set to True. It won't run clean but return
                  values for imszise and cell estimated for the longest
                  baseline in the data
    imsize -- Image pixel size (x,y).  DOES NOT HAVE TO BE A POWER OF 2
               default = [256,256]; example: imsize=[350,350]
               imsize = 500 is equivalent to [500,500].
               Avoid odd-numbered imsize.

    cell -- Cell size (x,y)
               default= '1.0arcsec';
               example: cell=['0.5arcsec,'0.5arcsec'] or
               cell=['1arcmin', '1arcmin']
               cell = '1arcsec' is equivalent to ['1arcsec','1arcsec']
               NOTE:cell = 2.0 => ['2arcsec', '2arcsec']

       phasecenter -- direction measure  or fieldid for the mosaic center
                default: '' => first field selected ; example: phasecenter=6
                or phasecenter='J2000 19h30m00 -40d00m00'

    mode -- this determines what kind of image to make
                continuum or cube. In continuum all the selected data
                channels are combined in a 1 channel image using
                multifrequency synthesis.
                options are 'cube' and 'continuum'
                default: 'continuum'
  >>> mode='cube' expandable parameters
               nchan -- sets the number of channel in the output
               image. e.g nchan=10
               width -- image channel width in terms of the number of
                        channel of the first spw of the data selected
                        e.g width=2  

    niter -- Maximum number of iterations,
               if niter=0, then no CLEANing is done ("invert" only)
               default: 500; example: niter=5000

    weighting -- Weighting to apply to visibilities:
               default='natural'; example: weighting='uniform';
               Options: 'natural','uniform','briggs',

    restoringbeam -- Output Gaussian restoring beam for CLEAN image
               [bmaj, bmin, bpa] elliptical Gaussian restoring beam.
               Default units are in arc-seconds for bmaj and bmin, and in degrees
               for bpa. Default: restoringbeam=[]; Use PSF calculated
               from dirty beam.
               example: restoringbeam=['10arcsec'] or restorinbeam='10arcsec', circular Gaussian.
                        FWHM 10 arcseconds example:
                        restoringbeam=['10.0','5.0','45.0deg'] 10"x5"
                        at 45 degrees
    interactive -- Create a mask interactively or not.
                default=False; example: interactive=True
                The viewer will open with the image displayed. Select the
                region for the mask and double click in the middle of it.