code: def astype(self, dtype):
          
          if dtype not in _supported_dtypes:
              raise ValueError('Datatype %s not supported. Supported types are %s' % (dtype, _supported_dtypes))
  
          pixeltype = _npy_to_itk_map[dtype]
          return self.clone(pixeltype)
docs: Cast & clone an ANTsImage to a given numpy datatype.
  
          Map:
              uint8   : unsigned char
              uint32  : unsigned int
              float32 : float
              float64 : double