code: def __draw_threshold_text(
      fairness_threshold,
      ref_group,
      chart_height,
      accessibility_mode=False,
      warnings=(),
  ):
      """Draw text that helps to read the threshold elements of the chart."""
      font_color = (
          Annotation.font_color
          if accessibility_mode
          else Annotation.font_color_threshold
      )
      warn_text = alt.Chart(DUMMY_DF).mark_text(
          baseline="top",
          align="left",
          font=FONT,
          fill=font_color,
          fontSize=Annotation.font_size,
          fontWeight=Annotation.font_weight,
      )
      n_warnings = 0
      text_explanation = []
      for group, metric in warnings:
          y_size = chart_height * (
              1 - 2 / 3 * Disparity_Chart.padding_y
          ) + Annotation.font_size * Annotation.line_spacing * (
              n_warnings + 1
          )
          explanation_text_warning = warn_text.encode(
              x=alt.value(0),
              y=alt.value(y_size),
              text=alt.value(
                  f"Groups {group} have {metric} of 0 (zero). This "
                  "does not allow for the calculation of relative disparities. "
                  "The groups will be absent in respective visualizations.",
              ),
          )
          n_warnings += 1
          text_explanation.append(explanation_text_warning)
      threshold_text = (
          alt.Chart(DUMMY_DF)
          .mark_text(
              baseline="top",
              align="left",
              font=FONT,
              fill=font_color,
              fontSize=Annotation.font_size,
              fontWeight=Annotation.font_weight,
              tooltip=None,
          )
          .encode(
              x=alt.value(0),
              y=alt.value(
                  chart_height * (1 - 2 / 3 * Disparity_Chart.padding_y)
              ),
              text=alt.value(
                  f"The metric value for any group should not be {fairness_threshold} (or more) times smaller or larger than that of the reference group {ref_group}."
              ),
          )
      )
  
      text_explanation.append(threshold_text)
  
      return alt.layer(*(chart for chart in text_explanation))
  
imports: import math
  import altair
  import pandas
  from aequitas.plot.commons.helpers import no_axis, transform_ratio, get_chart_metadata
  from aequitas.plot.commons.legend import draw_legend
  from aequitas.plot.commons.scales import get_chart_size_range
  from aequitas.plot.commons.tooltips import get_tooltip_text_group_size, get_tooltip_text_disparity_explanation
  from aequitas.plot.commons.style.classes import Metric_Axis, Axis, Annotation, Reference_Rule, Threshold_Rule, Threshold_Band, Bubble, Chart_Title
  from aequitas.plot.commons.style.text import FONT, FONT_SIZE_SMALL
  from aequitas.plot.commons.style.sizes import Disparity_Chart
  from aequitas.plot.commons import initializers
  from aequitas.plot.commons import labels
label_desc: Use image node_id 9 for calling a global function with example usage: __draw_threshold_text(fairness_threshold, ref_group, chart_height, accessibility_mode, warnings) and returns: alt