docs: def count_special_chars(self, char, prev_char):
          """Update parenthesis counters"""
          if char == '(':
              self.parenthesis_count += 1
          elif char == ')':
              self.parenthesis_count -= 1
              if self.parenthesis_count < 0:
                  raise RMarkdownOptionParsingError(
                      'Option line "{}" has too many '
                      'closing parentheses'.format(self.line))
          elif char == '{':
              self.curly_bracket_count += 1
          elif char == '}':
              self.curly_bracket_count -= 1
              if self.curly_bracket_count < 0:
                  raise RMarkdownOptionParsingError(
                      'Option line "{}" has too many '
                      'closing curly brackets'.format(self.line))
          elif char == '[':
              self.square_bracket_count += 1
          elif char == ']':
              self.square_bracket_count -= 1
              if self.square_bracket_count < 0:
                  raise RMarkdownOptionParsingError(
                      'Option line "{}" has too many '
                      'closing square brackets'.format(self.line))
          elif char == "'" and prev_char != '\\':
              self.in_single_quote = not self.in_single_quote
          elif char == '"' and prev_char != '\\':
              self.in_double_quote = not self.in_double_quote