How to use the branca.colormap.LinearColormap function in branca

def test_simple_linear():
    linear = cm.LinearColormap(['green', 'yellow', 'red'], vmin=3., vmax=10.)
    linear = cm.LinearColormap(['red', 'orange', 'yellow', 'green'],
                               index=[0, 0.1, 0.9, 1.])
    linear._repr_html_()

def __init__(self):
        self._schemes = _schemes.copy()
        self._colormaps = {key: LinearColormap(val) for
                           key, val in _schemes.items()}
        for key, val in _schemes.items():
            setattr(self, key, LinearColormap(val))

def __init__(self, positions, colors, colormap=None, nb_steps=12,
                 weight=None, opacity=None, **kwargs):
        super(ColorLine, self).__init__(**kwargs)
        self._name = 'ColorLine'
        positions = validate_locations(positions)

        if colormap is None:
            cm = LinearColormap(['green', 'yellow', 'red'],
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        elif isinstance(colormap, LinearColormap):
            cm = colormap.to_step(nb_steps)
        elif isinstance(colormap, list) or isinstance(colormap, tuple):
            cm = LinearColormap(colormap,
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        else:
            cm = colormap
        out = {}
        for (lat1, lng1), (lat2, lng2), color in zip(positions[:-1], positions[1:], colors):  # noqa
            out.setdefault(cm(color), []).append([[lat1, lng1], [lat2, lng2]])
        for key, val in out.items():
            self.add_child(PolyLine(val, color=key, weight=weight, opacity=opacity))  # noqa

Parameters
        ----------
        index : list of floats, default None
                The values corresponding to each color in the output colormap.
                It has to be sorted.
                If None, a regular grid between `vmin` and `vmax` is created.

        """
        if index is None:
            n = len(self.index)-1
            index = [self.index[i]*(1.-i/(n-1.))+self.index[i+1]*i/(n-1.) for
                     i in range(n)]

        colors = [self.rgba_floats_tuple(x) for x in index]
        return LinearColormap(colors, index=index,
                              vmin=self.vmin, vmax=self.vmax)

def __init__(self, positions, colors, colormap=None, nb_steps=12,
                 weight=None, opacity=None, **kwargs):
        super(ColorLine, self).__init__(**kwargs)
        self._name = 'ColorLine'
        positions = validate_locations(positions)

        if colormap is None:
            cm = LinearColormap(['green', 'yellow', 'red'],
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        elif isinstance(colormap, LinearColormap):
            cm = colormap.to_step(nb_steps)
        elif isinstance(colormap, list) or isinstance(colormap, tuple):
            cm = LinearColormap(colormap,
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        else:
            cm = colormap
        out = {}
        for (lat1, lng1), (lat2, lng2), color in zip(positions[:-1], positions[1:], colors):  # noqa
            out.setdefault(cm(color), []).append([[lat1, lng1], [lat2, lng2]])
        for key, val in out.items():
            self.add_child(PolyLine(val, color=key, weight=weight, opacity=opacity))  # noqa

def scale(self, vmin=0., vmax=1.):
        """Transforms the colorscale so that the minimal and maximal values
        fit the given parameters.
        """
        return LinearColormap(
            self.colors,
            index=[vmin + (vmax-vmin)*(x-self.vmin)*1./(self.vmax-self.vmin) for x in self.index],  # noqa
            vmin=vmin,
            vmax=vmax,
            caption=self.caption,
            )

def __init__(self, positions, colors, colormap=None, nb_steps=12,
                 weight=None, opacity=None, **kwargs):
        super(ColorLine, self).__init__(**kwargs)
        self._name = 'ColorLine'
        positions = validate_locations(positions)

        if colormap is None:
            cm = LinearColormap(['green', 'yellow', 'red'],
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        elif isinstance(colormap, LinearColormap):
            cm = colormap.to_step(nb_steps)
        elif isinstance(colormap, list) or isinstance(colormap, tuple):
            cm = LinearColormap(colormap,
                                vmin=min(colors),
                                vmax=max(colors),
                                ).to_step(nb_steps)
        else:
            cm = colormap
        out = {}
        for (lat1, lng1), (lat2, lng2), color in zip(positions[:-1], positions[1:], colors):  # noqa
            out.setdefault(cm(color), []).append([[lat1, lng1], [lat2, lng2]])
        for key, val in out.items():