code: def iMath_propagate_labels_through_mask(image, labels, stopping_value=100, propagation_method=0):
      
      return iMath(image, 'PropagateLabelsThroughMask', labels, stopping_value, propagation_method)
docs: >>> import ants
      >>> wms = ants.image_read('~/desktop/wms.nii.gz')
      >>> thal = ants.image_read('~/desktop/thal.nii.gz')
      >>> img2 = ants.iMath_propagate_labels_through_mask(wms, thal, 500, 0)