class_docstr: ProgressBar class keeps an update of the iteration and output the corresponding update progress bar.
  
  Args:
      steps (int): The number of steps.
      bar_format (str, optional): User defined format for the bar_format. By default the setting is
          {percentage} |{bar}|. The two argument must be {percentage} and {bar}.
      bar_character (str): The bar character to use. (Default value = █ which is 'block'.)
      partial_bar_characters (str): A list of character to use when a fraction of the bar character
          could be used. (Default value =
          ``[" ", "▏", "▎", "▍", "▌", "▋", "▊", "▉"]``
          that is from " " through 1/8th to 7/8th blocks)
  
  Attributes:
      total_steps (int): The total steps to do.
      bar_format (str): The format of the bar.
      bar_character (str): The bar character.
      bar_length (int): The size of the bar.
      actual_steps (int): Number of steps done so far.
docstr: To format the progress bar for an output.
docstr_tok: ["To","format","the","progress","bar","for","an","output","."]
code: def __str__(self):
      """
      To format the progress bar for an output.
      """
      percentage = f"{self.actual_steps / self.total_steps * 100:6.2f}%"
  
      progress_bar = self.progress_bar_formatting()
  
      return self.bar_format.format(
          percentage=percentage, bar=progress_bar
      )
  
imports: import math
  from typing import Optional
label_desc: Use image node_id 4 for calling the ProgressBar obj's underlying member method code with example usage: obj.__str__() and returns: self