code: def image_psf_shape_tag_from_image_psf_shape(image_psf_shape):
      
      if image_psf_shape is None:
          return ''
      else:
          y = str(image_psf_shape[0])
          x = str(image_psf_shape[1])
          return ('_image_psf_' + y + 'x' + x)
docs: Generate an image psf shape tag, to customize phase names based on size of the image PSF that the original PSF \
      is trimmed to for faster run times.
  
      This changes the phase name 'phase_name' as follows:
  
      image_psf_shape = 1 -> phase_name
      image_psf_shape = 2 -> phase_name_image_psf_shape_2
      image_psf_shape = 2 -> phase_name_image_psf_shape_2