class_docstr: Processes a file and holds state.
  
  This processes a file by generating tokens, logical and physical lines,
  and AST trees. This also provides a way of passing state about the file
  to checks expecting that state. Any public attribute on this object can
  be requested by a plugin. The known public attributes are:
  
  - :attr:`blank_before`
  - :attr:`blank_lines`
  - :attr:`checker_state`
  - :attr:`indent_char`
  - :attr:`indent_level`
  - :attr:`line_number`
  - :attr:`logical_line`
  - :attr:`max_line_length`
  - :attr:`max_doc_length`
  - :attr:`multiline`
  - :attr:`noqa`
  - :attr:`previous_indent_level`
  - :attr:`previous_logical`
  - :attr:`previous_unindented_logical_line`
  - :attr:`tokens`
  - :attr:`file_tokens`
  - :attr:`total_lines`
  - :attr:`verbose`
class_docstr_tok: ["Processes","a","file","and","holds","state",".","This","processes","a","file","by","generating","tokens",",","logical","and","physical","lines",",","and","AST","trees",".","This","also","provides","a","way","of","passing","state","about","the","file","to","checks","expecting","that","state",".","Any","public","attribute","on","this","object","can","be","requested","by","a","plugin",".","The","known","public","attributes","are",":","-",":","attr",":","`","blank_before","`","-",":","attr",":","`","blank_lines","`","-",":","attr",":","`","checker_state","`","-",":","attr",":","`","indent_char","`","-",":","attr",":","`","indent_level","`","-",":","attr",":","`","line_number","`","-",":","attr",":","`","logical_line","`","-",":","attr",":","`","max_line_length","`","-",":","attr",":","`","max_doc_length","`","-",":","attr",":","`","multiline","`","-",":","attr",":","`","noqa","`","-",":","attr",":","`","previous_indent_level","`","-",":","attr",":","`","previous_logical","`","-",":","attr",":","`","previous_unindented_logical_line","`","-",":","attr",":","`","tokens","`","-",":","attr",":","`","file_tokens","`","-",":","attr",":","`","total_lines","`","-",":","attr",":","`","verbose","`"]
docstr: Signal the beginning of an fstring.
docstr_tok: ["Signal","the","beginning","of","an","fstring","."]
code: def fstring_start(self, lineno: int) -> None:  # pragma: >=3.12 cover
      """Signal the beginning of an fstring."""
      self._fstring_start = lineno
  
imports: from __future__ import annotations
  import argparse
  import ast
  import functools
  import logging
  import tokenize
  from typing import Any
  from typing import Generator
  from typing import List
  from typing import Tuple
  from flake8 import defaults
  from flake8 import utils
  from flake8._compat import FSTRING_END
  from flake8._compat import FSTRING_MIDDLE
  from flake8.plugins.finder import LoadedPlugin
label_desc: Use image node_id 3 for calling the FileProcessor obj's underlying member method code with example usage: obj.fstring_start(lineno) without return types