docs: def _colorize(token,  # type: str
                weight,  # type: float
                weight_range,  # type: float
                ):
      # type: (...) -> str
      """ Return token wrapped in a span with some styles
      (calculated from weight and weight_range) applied.
      """
      token = html_escape(token)
      if np.isclose(weight, 0.):
          return (
              '<span '
              'style="opacity: {opacity}"'
              '>{token}</span>'.format(
                  opacity=_weight_opacity(weight, weight_range),
                  token=token)
          )
      else:
          return (
              '<span '
              'style="background-color: {color}; opacity: {opacity}" '
              'title="{weight:.3f}"'
              '>{token}</span>'.format(
                  color=format_hsl(
                      weight_color_hsl(weight, weight_range, min_lightness=0.6)),
                  opacity=_weight_opacity(weight, weight_range),
                  weight=weight,
                  token=token)
          )