peerPrefixS3    = "peerS3"
	healPrefix      = "heal"
)

func init() {
	// Static check if we exceed 255 handler ids.
	// Extend the type to uint16 when hit.
	if uint32(handlerLast) > 255 {
		panic(fmt.Sprintf("out of handler IDs. %d > %d", handlerLast, 255))
	}
}

func (h HandlerID) valid() bool {
	return h != handlerInvalid && h < handlerLast
}

func (h HandlerID) isTestHandler() bool {

```Python hl_lines="2-5  15  21"
{!../../docs_src/handling_errors/tutorial006.py!}
```

			}
			return written, nil
		}
	}
}

// SafeClose safely closes any channel of any type
func SafeClose[T any](c chan<- T) {
	if c != nil {
		close(c)
		return
	}
	// Print stack to check who is sending `c` as `nil`
	// without crashing the server.
	debug.PrintStack()

		return
	}

	cfg, err := readServerConfig(ctx, objectAPI, nil)
	if err != nil {
		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
		return
	}

	cfgKey := fmt.Sprintf("%s:%s", subSys, cfgName)
	if cfgName == madmin.Default {
		cfgKey = subSys
	}
	if err = cfg.DelKVS(cfgKey); err != nil {
		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
		return
	}

			valid: true,
		},
		{
			name:  "metric labels istio canonical",
			in:    validIstioCanonical,
			valid: true,
		},
	}

	for i, c := range cases {
		t.Run(fmt.Sprintf("[%v] %v ", i, c.name), func(tt *testing.T) {
			defer func() { recover() }()
			v := &validator{}
			var writer io.Writer
			warn, err := v.validateResource("istio-system", "", fromYAML(c.in), writer)

{* ../../docs_src/python_types/tutorial001.py hl[2] *}

### Edit it

It's a very simple program.

But now imagine that you were writing it from scratch.

At some point you would have started the definition of the function, you had the parameters ready...

But then you have to call "that method that converts the first letter to upper case".

    // Ascii.equalsIgnoreCase(), but it is a signal that its documentation may need updating as
    // regards edge cases.

    // The Unicode point {@code 00df} is the lowercase form of sharp-S (ß), whose uppercase is "SS".
    assertEquals("PASSWORD", "pa\u00dfword".toUpperCase()); // [*]
    assertFalse("pa\u00dfword".equalsIgnoreCase("PASSWORD")); // [*]

RUN groupadd -g 1001 buildslave && useradd -m -u 1001 -g buildslave buildslave
RUN mkdir -p /tf/venv
RUN chown -R buildslave:buildslave /tf
RUN dpkg -i /patchelf/patchelf_0.14.3-1_arm64.deb

# All lines past this point are reset when $CACHEBUSTER is set. We need this
# for Python specifically because we install some nightly packages which are
# likely to change daily.
ARG CACHEBUSTER=0
RUN echo $CACHEBUSTER

# Setup build and environment

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

在底层，`open("./somefile.txt")`创建了一个被称为"上下文管理器"的对象。

当 `with` 代码块结束时，它会确保关闭文件，即使发生了异常也是如此。

当你使用 `yield` 创建一个依赖项时，**FastAPI** 会在内部将其转换为上下文管理器，并与其他相关工具结合使用。

### 在使用 `yield` 的依赖项中使用上下文管理器

	atTotal := uint64(0)
	for _, pool := range serverPools {
		atTotal += pool.Available
		if atTotal > choose && pool.Available > 0 {
			return pool.Index
		}
	}
	// Should not happen, but print values just in case.
	storageLogIf(ctx, fmt.Errorf("reached end of serverPools (total: %v, atTotal: %v, choose: %v)", total, atTotal, choose))
	return -1
}