Repository: ManimCommunity/manim
File: manim/mobject/graphing/probability.py (Python)

Code before:
            x_length=x_length,
            y_length=y_length,
            x_axis_config=x_axis_config,
            tips=kwargs.pop("tips", False),
            **kwargs,
        )

        self._add_bars()

        if self.bar_names is not None:
            self._add_x_axis_labels()

        self.y_axis.add_numbers()

    def _update_colors(self):
        """Initialize the colors of the bars of the chart.

        Sets the color of ``self.bars`` via ``self.bar_colors``.

        Primarily used when the bars are initialized with ``self._add_bars``
        or updated via ``self.change_bar_values``.
        """
        if isinstance(self.bar_colors, str):
            self.bars.set_color_by_gradient(self.bar_colors)
        else:
            self.bars.set_color_by_gradient(*self.bar_colors)

    def _add_x_axis_labels(self):
        """Essentially ``:meth:~.NumberLine.add_labels``, but differs in that
        the direction of the label with respect to the x_axis changes to UP or DOWN
        depending on the value.

        UP for negative values and DOWN for positive values.
        """

        val_range = np.arange(
            0.5, len(self.bar_names), 1
        )  # 0.5 shifted so that labels are centered, not on ticks

        labels = VGroup()

        for i, (value, bar_name) in enumerate(zip(val_range, self.bar_names)):
            # to accommodate negative bars, the label may need to be
            # below or above the x_axis depending on the value of the bar
            if self.values[i] < 0:
                direction = UP
            else:
                direction = DOWN
            bar_name_label = self.x_axis.label_constructor(bar_name)

            bar_name_label.font_size = self.x_axis.font_size

Review comment (refactor):
Given that the type hint for `bar_colors` also supports `str` I think this is fine for that but since `bar_colors` is plural can we not just tell the user to always enter the values in a list? 
And remove this function entirely and just put in `self.bars.set_color_by_gradient(*self.bar_colors)` in place of where it is called?

Code after:
        self.bars: VGroup = VGroup()
        self.x_labels: VGroup | None = None
        self.bar_labels: VGroup | None = None

        super().__init__(
            x_range=x_range,
            y_range=y_range,
            x_length=x_length,
            y_length=y_length,
            x_axis_config=x_axis_config,
            tips=kwargs.pop("tips", False),
            **kwargs,
        )

        self._add_bars()

        if self.bar_names is not None:
            self._add_x_axis_labels()

        self.y_axis.add_numbers()

    def _update_colors(self):
        """Initialize the colors of the bars of the chart.

        Sets the color of ``self.bars`` via ``self.bar_colors``.

        Primarily used when the bars are initialized with ``self._add_bars``
        or updated via ``self.change_bar_values``.
        """

        self.bars.set_color_by_gradient(*self.bar_colors)

    def _add_x_axis_labels(self):
        """Essentially :meth`:~.NumberLine.add_labels`, but differs in that
        the direction of the label with respect to the x_axis changes to UP or DOWN
        depending on the value.

        UP for negative values and DOWN for positive values.
        """

        val_range = np.arange(
            0.5, len(self.bar_names), 1
        )  # 0.5 shifted so that labels are centered, not on ticks

        labels = VGroup()

        for i, (value, bar_name) in enumerate(zip(val_range, self.bar_names)):
            # to accommodate negative bars, the label may need to be
            # below or above the x_axis depending on the value of the bar
            if self.values[i] < 0:
                direction = UP