On this page
numpy.ma.soften_mask
numpy.ma.soften_mask(self) = <numpy.ma.core._frommethod object>- 
    
Force the mask to soft.
Whether the mask of a masked array is hard or soft is determined by its
hardmaskproperty.soften_masksetshardmaskto False.See also
hardmask 
© 2005–2019 NumPy Developers
Licensed under the 3-clause BSD License.
 https://docs.scipy.org/doc/numpy-1.16.1/reference/generated/numpy.ma.soften_mask.html