• The variable names in change_char_at are terrible. s for the string, ch for the char? i for the start? j for the end.

  Seriously just write out names.

  def change_char_at(string: str, change: str, start: int, end: int = None):
      return string[:start] + change + string[end or start+1:]
  

• Your code isn't fully typed:

  • change_char_at has no return type.
  • end in change_char_at and wait in loader_with_wait are assumed to be Optional but not specified to be optional.
  • loader and loader_with_wait have no return types should they be None or NoReturn?

• The functionallity of change_char_at can be eclipsed by the format mini-language.

  1. You have a standard structure where the bar is surrounded by [] and filled with the contents.

     bar = '[{}]'
     

  2. The content of your bar is left aligned by width.

     bar = '[{: <{width}}]'
     

  3. Each iteration the contents is increased by 1 equals.

     bar.format('=' * (i + bar_width), width=width)
     

• bar_width doesn't actually change the size of the bar.

• I would prefer the progress bar to be a generator function or list, so the rest of your code is simpler.

def progress_bar(width: int = 20, bar_width: int = 3):
    bar = f'[{{: <{width}}}]'
    for i in range(bar_width, width):
        yield bar.format('=' * i)

• The variable names in change_char_at are terrible. s for the string, ch for the char? i for the start? j for the end.

  Seriously just write out names.

  def change_char_at(string: str, change: str, start: int, end: int = None):
      return string[:start] + change + string[end or start+1:]
  

• Your code isn't fully typed:

  • change_char_at has no return type.
  • end in change_char_at and wait in loader_with_wait are assumed to be Optional but not specified to be optional.
  • loader and loader_with_wait have no return types should they be None or NoReturn?

• The functionallity of change_char_at can be eclipsed by the format mini-language.

  1. You have a standard structure where the bar is surrounded by [] and filled with the contents.

     bar = '[{}]'
     

  2. The content of your bar is left aligned by width.

     bar = '[{: <{width}}]'
     

  3. Each iteration you increase the left hand space by 1.

     bar.format(' ' * i + '=' * bar_width, width=width)
     

• bar_width doesn't actually change the size of the bar.

• I would prefer the progress bar to be a generator function or list, so the rest of your code is simpler.

import itertools


def progress_bar(width: int = 20, bar_width: int = 3):
    bar = f'[{{: <{width}}}]'
    for i in itertools.chain(
        range(0, width - bar_width + 1),
        reversed(range(0, width - bar_width)),
    ):
        yield bar.format(' ' * i + '=' * bar_width)