This practice is common enough that it has a name, these environment variables are commonly placed in a file `.env`, and the file is called a "dotenv".

!!! tip
    A file starting with a dot (`.`) is a hidden file in Unix-like systems, like Linux and macOS.

    But a dotenv file doesn't really have to have that exact filename.

  // IngressRuleValue. If the host is unspecified, the Ingress routes all
  // traffic based on the specified IngressRuleValue.
  //
  // host can be "precise" which is a domain name without the terminating dot of
  // a network host (e.g. "foo.bar.com") or "wildcard", which is a domain name
  // prefixed with a single wildcard label (e.g. "*.foo.com").
  // The wildcard character '*' must appear by itself as the first DNS label and

  fun secure(): Boolean = secure

  /**
   * @param forObsoleteRfc2965 true to include a leading `.` on the domain pattern. This is
   *     necessary for `example.com` to match `www.example.com` under RFC 2965. This extra dot is
   *     ignored by more recent specifications.
   */
  internal fun toString(forObsoleteRfc2965: Boolean): String {
    return buildString {
      append(name)
      append('=')
      append(value)

      apply {
        assertThat(index, "No more messages found")
          .isLessThan(logs.size)
        assertThat(logs[index++])
          .matches(Regex(prefix.pattern + regex.pattern, RegexOption.DOT_MATCHES_ALL))
      }

    fun assertNoMoreLogs() {
      assertThat(logs.size, "More messages remain: ${logs.subList(index, logs.size)}")
        .isEqualTo(index)
    }

Was it `upper`? Was it `uppercase`? `first_uppercase`? `capitalize`?

Then, you try with the old programmer's friend, editor autocompletion.

You type the first parameter of the function, `first_name`, then a dot (`.`) and then hit `Ctrl+Space` to trigger the completion.

But, sadly, you get nothing useful:

<img src="/img/python-types/image01.png">

### Add types

Let's modify a single line from the previous version.

  // Accessible property names are escaped according to the following rules when accessed in the expression:
  // - '__' escapes to '__underscores__'
  // - '.' escapes to '__dot__'
  // - '-' escapes to '__dash__'
  // - '/' escapes to '__slash__'
  // - Property names that exactly match a CEL RESERVED keyword escape to '__{keyword}__'. The keywords are:

	return p.records
}

// Stop the currently running benchmark.
func (p profilerWrapper) Stop() ([]byte, error) {
	return p.stopFn()
}

// Extension returns the extension without dot prefix.
func (p profilerWrapper) Extension() string {
	return p.ext
}

// Returns current profile data, returns error if there is no active
// profiling in progress. Stops an active profile.

		{"bucket1", true},
		{"$this-is-not-valid-too", true},
		{"contains-$-dollar", true},
		{"contains-^-carrot", true},
		{"contains-$-dollar", true},
		{"contains-$-dollar", true},
		{".starts-with-a-dot", true},
		{"ends-with-a-dot.", true},
		{"ends-with-a-dash-", true},
		{"-starts-with-a-dash", true},
		{"THIS-BEINGS-WITH-UPPERCASe", true},
		{"tHIS-ENDS-WITH-UPPERCASE", true},
		{"ThisBeginsAndEndsWithUpperCase", true},

	// Special case when bucket is equal to one of the meta buckets.
	if isMinioMetaBucketName(bucket) {
		return true
	}
	if len(bucket) < 3 || len(bucket) > 63 {
		return false
	}

	// Split on dot and check each piece conforms to rules.
	allNumbers := true
	pieces := strings.Split(bucket, dnsDelimiter)
	for _, piece := range pieces {
		if len(piece) == 0 || piece[0] == '-' ||
			piece[len(piece)-1] == '-' {

		if err != nil {
			c.Fatalf("normalize err: %v", err)
		}
		return normalizedDN
	}

	actualUserDN := mustNormalizeDN("uid=svc.algorithm,OU=swengg,DC=min,DC=io")

	// \uFE52 is the unicode dot SMALL FULL STOP used below:
	userDNWithUnicodeDot := "uid=svc﹒algorithm,OU=swengg,DC=min,DC=io"

	if err = s.adm.SetPolicy(ctx, policy, userDNWithUnicodeDot, false); err != nil {
		c.Fatalf("Unable to set policy: %v", err)