# Header Parameters { #header-parameters }

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

A middleware doesn't have to be made for FastAPI or Starlette to work, as long as it follows the ASGI spec.

In general, ASGI middlewares are classes that expect to receive an ASGI app as the first argument.

So, in the documentation for third-party ASGI middlewares they will probably tell you to do something like:

```Python
from unicorn import UnicornMiddleware

app = SomeASGIApp()

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

</div>

////

     */
    public boolean atMost(final DialectVersion v) {
        return ordinal() <= v.ordinal();
    }

    /**
     * Get the minimum of two dialect versions
     *
     * @param a the first version to compare
     * @param b the second version to compare
     * @return smaller of the two versions
     */
    public static DialectVersion min(final DialectVersion a, final DialectVersion b) {

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	stmt := newDB.First(&result).Statement
	str := stmt.SQL.String()

	if !strings.Contains(str, "rgs.id = user.id") {
		t.Errorf("The second join condition is over written instead of combining")
	}

	if !strings.Contains(str, "`users`.`company_id` = `companies`.`id`") && !strings.Contains(str, "\"users\".\"company_id\" = \"companies\".\"id\"") {

            throw new IllegalArgumentException("Share name contains invalid characters: " + share);
        }
    }

    /**
     * Validates integer for safe arithmetic operations
     *
     * @param a first operand
     * @param b second operand
     * @param operation the operation name
     * @throws ArithmeticException if operation would overflow
     */

        // Wait for reset timeout
        Thread.sleep(1100);

        // First success should transition to HALF_OPEN
        String result = circuitBreaker.executeWithCircuitBreaker(() -> "success 0");
        assertEquals("success 0", result, "Should execute in HALF_OPEN");
        assertEquals(State.HALF_OPEN, circuitBreaker.getState(), "Should be in HALF_OPEN after first success");

        String sessionId = "test_replace";
        List<String> cmdList1 = Arrays.asList("echo", "first");
        List<String> cmdList2 = Arrays.asList("echo", "second");
        Consumer<ProcessBuilder> pbCall = pb -> {
            pb.redirectErrorStream(true);
        };

        try {
            // Start first process
            JobProcess jobProcess1 = processHelper.startProcess(sessionId, cmdList1, pbCall);

        assertNotNull(entry2);
        assertEquals(DirectoryCacheScope.IMMEDIATE_CHILDREN, entry1.getScope());
        assertEquals(DirectoryCacheScope.RECURSIVE_TREE, entry2.getScope());

        // Update first directory cache
        List<SmbFile> files1 = Arrays.asList(mockFile1);
        directoryLeaseManager.updateDirectoryCache(dir1, files1);

        // Update second directory cache