class_docstr: A reader of fixed-width lines.
code: def __next__(self) -> list[str]:
      # Argument 1 to "next" has incompatible type "Union[IO[str],
      # ReadCsvBuffer[str]]"; expected "SupportsNext[str]"
      if self.buffer is not None:
          try:
              line = next(self.buffer)
          except StopIteration:
              self.buffer = None
              line = next(self.f)  # type: ignore[arg-type]
      else:
          line = next(self.f)  # type: ignore[arg-type]
      # Note: 'colspecs' is a sequence of half-open intervals.
      return [
          line[from_:to].strip(self.delimiter)
          for (from_, to) in self.colspecs
      ]
  
imports: from __future__ import annotations
  from collections import abc, defaultdict
  import csv
  from io import StringIO
  import re
  import sys
  from typing import IO, TYPE_CHECKING, DefaultDict, Hashable, Iterator, List, Literal, Mapping, Sequence, cast
  import numpy
  from pandas._libs import lib
  from pandas._typing import ArrayLike, ReadCsvBuffer, Scalar
  from pandas.errors import EmptyDataError, ParserError
  from pandas.core.dtypes.common import is_integer
  from pandas.core.dtypes.inference import is_dict_like
  from pandas.io.common import dedup_names, is_potential_multi_index
  from pandas.io.parsers.base_parser import ParserBase, parser_defaults
label_desc: Use image node_id 4 for calling the FixedWidthReader obj's underlying member method code with example usage: obj.__next__() and returns: unknown