# Buggy code
def parse_file(self, f, fname=None, verbosity=0, recurse=True):
    violations = []
    t0 = get_time()

    # Allow f to optionally be a raw string
    if isinstance(f, str):
        # Add it to a buffer if that's what we're doing
        f = StringIO(f)

    verbosity_logger("LEXING RAW ({0})".format(fname), verbosity=verbosity)
    # Lex the file and log any problems
    try:
        fs = FileSegment.from_raw(f.read())
    except SQLLexError as err:
        violations.append(err)
        fs = None

    if fs:
        verbosity_logger(fs.stringify(), verbosity=verbosity)

    t1 = get_time()
    verbosity_logger("PARSING ({0})".format(fname), verbosity=verbosity)
    # Parse the file and log any problems
    if fs:
        try:
            parsed = fs.parse(
                recurse=recurse, verbosity=verbosity, dialect=self.dialect
            )
        except SQLParseError as err:
            violations.append(err)
            parsed = None
        if parsed:
            verbosity_logger(frame_msg("Parsed Tree:"), verbosity=verbosity)
            verbosity_logger(parsed.stringify(), verbosity=verbosity)
    else:
        parsed = None

    t2 = get_time()
    time_dict = {"lexing": t1 - t0, "parsing": t2 - t1}

    return parsed, violations, time_dict


# Traceback (TypeError)
Traceback (most recent call last):
File "/home/user/sql/.venv/bin/sqlfluff", line 11, in <module>
load_entry_point('sqlfluff==0.1.3', 'console_scripts', 'sqlfluff')()
File "/home/user/sql/.venv/lib/python3.7/site-packages/click/core.py", line 764, in __call__
return self.main(*args, **kwargs)
File "/home/user/sql/.venv/lib/python3.7/site-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
File "/home/user/sql/.venv/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/home/user/sql/.venv/lib/python3.7/site-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/user/sql/.venv/lib/python3.7/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/cli/commands.py", line 85, in lint
result = lnt.lint_paths(paths, verbosity=verbose)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/linter.py", line 324, in lint_paths
result.add(self.lint_path(path, verbosity=verbosity, fix=fix))
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/linter.py", line 312, in lint_path
linted_path.add(self.lint_file(f, fname=fname, verbosity=verbosity, fix=fix))
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/linter.py", line 212, in lint_file
parsed, vs, time_dict = self.parse_file(f=f, fname=fname, verbosity=verbosity)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/linter.py", line 193, in parse_file
parsed = fs.parse(recurse=recurse, verbosity=verbosity, dialect=self.dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 228, in parse
verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 394, in expand
res = stmt.parse(recurse=recurse, parse_depth=parse_depth, verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 228, in parse
verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 394, in expand
res = stmt.parse(recurse=recurse, parse_depth=parse_depth, verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 228, in parse
verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 394, in expand
res = stmt.parse(recurse=recurse, parse_depth=parse_depth, verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 228, in parse
verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 394, in expand
res = stmt.parse(recurse=recurse, parse_depth=parse_depth, verbosity=verbosity, dialect=dialect)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 186, in parse
dialect=dialect, match_segment=self.__class__.__name__)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 70, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 273, in match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 70, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 485, in match
match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 70, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 273, in match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 70, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 236, in match
dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 361, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/segments_base.py", line 320, in match
dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 70, in _match
verbosity=verbosity, dialect=dialect, match_segment=match_segment)
File "/home/user/sql/.venv/lib/python3.7/site-packages/sqlfluff/parser/grammar.py", line 586, in match
segment=segments[start_bracket_idx])
TypeError: tuple indices must be integers or slices, not NoneType

# Fixed code
def parse_file(self, f, fname=None, verbosity=0, recurse=True):
    violations = []
    t0 = get_time()

    # Allow f to optionally be a raw string
    if isinstance(f, str):
        # Add it to a buffer if that's what we're doing
        f = StringIO(f)

    verbosity_logger("LEXING RAW ({0})".format(fname), verbosity=verbosity)
    # Lex the file and log any problems
    try:
        fs = FileSegment.from_raw(f.read())
    except SQLLexError as err:
        violations.append(err)
        fs = None

    if fs:
        verbosity_logger(fs.stringify(), verbosity=verbosity)

    t1 = get_time()
    verbosity_logger("PARSING ({0})".format(fname), verbosity=verbosity)
    # Parse the file and log any problems
    if fs:
        try:
            # Make a parse context and parse
            context = ParseContext(
                dialect=self.dialect, verbosity=verbosity, recurse=recurse
            )
            parsed = fs.parse(parse_context=context)
        except SQLParseError as err:
            violations.append(err)
            parsed = None
        if parsed:
            verbosity_logger(frame_msg("Parsed Tree:"), verbosity=verbosity)
            verbosity_logger(parsed.stringify(), verbosity=verbosity)
    else:
        parsed = None

    t2 = get_time()
    time_dict = {"lexing": t1 - t0, "parsing": t2 - t1}

    return parsed, violations, time_dict