code: def vline(level, **kwargs):
      """Draws a vertical line at the given level.
  
      Parameters
      ----------
      level: float
          The level at which to draw the vertical line.
      preserve_domain: boolean (default: False)
          If true, the line does not affect the domain of the 'x' scale.
      """
      kwargs.setdefault("colors", ["dodgerblue"])
      kwargs.setdefault("stroke_width", 1)
      scales = kwargs.pop("scales", {})
      fig = kwargs.get("figure", current_figure())
      scales["y"] = fig.scale_y
  
      level = array(level)
      if len(level.shape) == 0:
          x = [level, level]
          y = [0, 1]
      else:
          x = column_stack([level, level])
          # TODO: repeating [0, 1] should not be required once we allow for
          # 2-D x and 1-D y
          y = [[0, 1]] * len(level)
      return plot(
          x,
          y,
          scales=scales,
          preserve_domain={
              "x": kwargs.get("preserve_domain", False),
              "y": True,
          },
          axes=False,
          update_context=False,
          **kwargs,
      )
  
imports: import sys
  from collections import OrderedDict
  from IPython.display import display
  from ipywidgets import Image
  from numpy import arange, issubdtype, array, column_stack, shape
  from .figure import Figure
  from bqscales import Scale, LinearScale, Mercator
  from .axes import Axis
  from .marks import Lines, Scatter, Hist, Bars, OHLC, Pie, Map, Image, Label, HeatMap, GridHeatMap, topo_load, Boxplot, Bins
  from .interacts import BrushIntervalSelector, FastIntervalSelector, BrushSelector, IndexSelector, MultiSelector, LassoSelector
  from traitlets.utils.sentinel import Sentinel
  import functools
label_desc: Use image node_id 18 for calling a global function with example usage: vline(level) and returns: plot