```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

Использование `Optional[str]` вместо просто `str` позволит редактору помочь вам в обнаружении ошибок, в которых вы могли бы предположить, что значение всегда является `str`, хотя на самом деле это может быть и `None`.

#### Generic-типы

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

blank_issues_enabled: true
contact_links:
  - name: Questions
    about: Please use one of the forums for questions or general discussions

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

    'rate(%s[$__rate_interval])' % query,
  round(query, by=0.01):
    'round(%s, %s)' % [query, by],
  quantile(quantile, query):
    'histogram_quantile(%s, %s)' %[quantile, query],
  labels(metric_name, labels):
    // One can nest locals.
    // Every local ends with a semi-colon.
    local prom_labels = std.join(',',
      std.map(
        function(k)
          if std.startsWith(labels[k], "!~") then

   *
   * @since 8.0
   */
  public static final byte ETX = 3;

  /**
   * End of Transmission: A communication control character used to indicate the conclusion of a
   * transmission, which may have contained one or more texts and any associated headings.
   *
   * @since 8.0
   */
  public static final byte EOT = 4;

  /**
   * Enquiry: A communication control character used in data communication systems as a request for

 *
 * <h3>Building a {@code ValueGraph}</h3>
 *
 * <p>The implementation classes that {@code common.graph} provides are not public, by design. To
 * create an instance of one of the built-in implementations of {@code ValueGraph}, use the {@link
 * ValueGraphBuilder} class:
 *
 * <pre>{@code
 * MutableValueGraph<Integer, Double> graph = ValueGraphBuilder.directed().build();
 * }</pre>
 *

      .assertLogMatch(Regex("""connectEnd: http/1.1"""))
      .assertLogMatch(
        Regex(
          """connectionAcquired: Connection\{${url.host}:\d+, proxy=DIRECT hostAddress=${url.host}/.+ cipherSuite=none protocol=http/1\.1\}""",
        ),
      )
      .assertLogMatch(Regex("""requestHeadersStart"""))
      .assertLogMatch(Regex("""requestHeadersEnd"""))
      .assertLogMatch(Regex("""responseHeadersStart"""))

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

	flag.DurationVar(&goTime, "time", 0, "goroutine waiting for exactly the specified time")
	flag.DurationVar(&margin, "margin", 0, "margin time")
	flag.StringVar(&searchText, "search", "", "Regex to search for a text in one goroutine stacktrace")
}

func parseGoroutineType2(path string) (map[time.Duration][]string, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}

	bf := bytes.Buffer{}