docs: def to_masked_array(self, copy=True):
          """Convert this array into a numpy.ma.MaskedArray
  
          Parameters
          ----------
          copy : bool
              If True (default) make a copy of the array in the result. If False,
              a MaskedArray view of DataArray.values is returned.
  
          Returns
          -------
          result : MaskedArray
              Masked where invalid values (nan or inf) occur.
          """
          isnull = pd.isnull(self.values)
          return np.ma.MaskedArray(data=self.values, mask=isnull, copy=copy)