code: def set_dark_theme(custom_style: dict = None) -> None:
      """
      Set aspects of the visual theme for all matplotlib plots.
      This function changes the global defaults for all plots using the matplotlib
      rcParams system. The theme includes specific colors for figure and axes
      backgrounds, gridlines, text, labels, and ticks. It also sets the font size
      and line width.
  
      Parameters
      ----------
      custom_style : dict, default None
          Optional dictionary containing custom styles to be added or override the
          default dark theme. It is applied after the default theme is set by
          using the `plt.rcParams.update()` method.
  
      Returns
      -------
      None
  
      """
  
      plt.style.use("fivethirtyeight")
      dark_style = {
          "figure.facecolor": "#212946",
          "axes.facecolor": "#212946",
          "savefig.facecolor": "#212946",
          "axes.grid": True,
          "axes.grid.which": "both",
          "axes.spines.left": False,
          "axes.spines.right": False,
          "axes.spines.top": False,
          "axes.spines.bottom": False,
          "grid.color": "#2A3459",
          "grid.linewidth": "1",
          "text.color": "0.9",
          "axes.labelcolor": "0.9",
          "xtick.color": "0.9",
          "ytick.color": "0.9",
          "font.size": 10,
          "lines.linewidth": 1.5,
      }
  
      if custom_style is not None:
          dark_style.update(custom_style)
  
      plt.rcParams.update(dark_style)
  
file_path: skforecast/skforecast/plot/plot.py
imports: from typing import Union, Any, Optional
  import numpy
  import pandas
  from ..utils import check_optional_dependency
label_desc: Use image node_id 4 for calling a global function with example usage: set_dark_theme(custom_style) without return types