def fill(self, src, name=None):
        """Fill the surface between sources for a label defined in source space

        Parameters
        ----------
        src : SourceSpaces
            Source space in which the label was defined. If a source space is
            provided, the label is expanded to fill in surface vertices that
            lie between the vertices included in the source space. For the
            added vertices, ``pos`` is filled in with positions from the
            source space, and ``values`` is filled in from the closest source
            space vertex.
        name : None | str
            Name for the new Label (default is self.name).

        Returns
        -------
        label : Label
            The label covering the same vertices in source space but also
            including intermediate surface vertices.
        """
        # find source space patch info
        if self.hemi == 'lh':
            hemi_src = src[0]
        elif self.hemi == 'rh':
            hemi_src = src[1]

        if not np.all(in1d(self.vertices, hemi_src['vertno'])):
            msg = "Source space does not contain all of the label's vertices"
            raise ValueError(msg)

        nearest = hemi_src['nearest']
        if nearest is not None:
            warn("Computing patch info for source space, this can take "
                 "a while. In order to avoid this in the future, run "
                 "mne.add_source_space_distances() on the source space "
                 "and save it.")
            add_source_space_distances(src)
            nearest = hemi_src['nearest']

        # find new vertices
        include = in1d(nearest, self.vertices, False)
        vertices = np.nonzero(include)[0]

        # values
        nearest_in_label = digitize(nearest[vertices], self.vertices, True)
        values = self.values[nearest_in_label]
        # pos
        pos = hemi_src['rr'][vertices]

        if name is None:
            name = self.name
        label = Label(vertices, pos, values, self.hemi, self.comment, name,
                      None, self.subject, self.color)
        return label
dataset/ETHPy150Open mne-tools/mne-python/mne/label.py/Label.fill/operator `is` -> `is not`