code: def from_str(cls, s, name=None, fill_char=None, wrapper=None):
          
          fill_char = fill_char or cls.default_fill_char
          maxlen = len(s)
          frames = []
          for pos in range(1, maxlen):
              framestr = s[:pos]
              # Not using ljust, because fill_char may be a str, not a char.
              frames.append(
                  ''.join((
                      framestr,
                      fill_char * (maxlen - len(framestr))
                  ))
              )
          frames.append(s)
          return cls(
              frames,
              name=name,
              wrapper=wrapper,
          )
docs: Create progress bar frames from a single string.
              The frames simulate growth, from an empty string to the final
              string (`s`).
  
              Arguments:
                  s          : Final string for a complete progress bar.
                  name       : Name for the new BarSet.
                  fill_char  : Character to fill empty space.
                               Default: ' ' (space)
                  wrapper    : Wrapping characters for the new bar set.
                               Default: cls.default_wrapper