class_docstr: BalancedBinningReference generates a histogram with vertical lines
  showing the recommended value point to bin your data so they can be evenly
  distributed in each bin.
  
  Parameters
  ----------
  ax : matplotlib Axes, default: None
      This is inherited from FeatureVisualizer and is defined within
      ``BalancedBinningReference``.
  
  target : string, default: "y"
      The name of the ``y`` variable
  
  bins : number of bins to generate the histogram, default: 4
  
  kwargs : dict
      Keyword arguments that are passed to the base class and may influence
      the visualization as defined in other Visualizers.
  
  Attributes
  ----------
  bin_edges_ : binning reference values
  
  Examples
  --------
  >>> visualizer = BalancedBinningReference()
  >>> visualizer.fit(y)
  >>> visualizer.show()
  
  
  Notes
  -----
  These parameters can be influenced later on in the visualization
  process, but can and should be set as early as possible.
docstr: Draws a histogram with the reference value for binning as vertical
  lines.
  
  Parameters
  ----------
  y : an array of one dimension or a pandas Series
code: def draw(self, y, **kwargs):
      """
      Draws a histogram with the reference value for binning as vertical
      lines.
  
      Parameters
      ----------
      y : an array of one dimension or a pandas Series
      """
  
      # draw the histogram
      hist, bin_edges = np.histogram(y, bins=self.bins)
      self.bin_edges_ = bin_edges
      self.ax.hist(
          y,
          bins=self.bins,
          color=kwargs.pop("color", "#6897bb"),
          **kwargs,
      )
  
      # add vertical line with binning reference values
      self.ax.vlines(
          bin_edges, 0, max(hist), colors=kwargs.pop("colors", "r")
      )
  
      return self.ax
  
file_path: yellowbrick/yellowbrick/target/binning.py
imports: import numpy
  from yellowbrick.target.base import TargetVisualizer
  from yellowbrick.exceptions import YellowbrickValueError
label_desc: Use image node_id 2 for calling the BalancedBinningReference obj's underlying member method code with example usage: obj.draw(y) and returns: self