## What makes a dependency

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

A "**callable**" in Python is anything that Python can "call" like a function.

          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {
            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.
          requireNonNull(left);
          if (left.balanceFactor() < 0) {

max_wait  (duration)  maximum wait time between operations, defaults to '15s'
cycle     (duration)  time duration between scanner cycles
```

Example: the following setting will decrease the scanner speed by a factor of 3, reducing the system resource use, but increasing the latency of updates being reflected.

```sh
~ mc admin config set alias/ scanner delay=30.0
```

                  }
                ],
                "load_balancing_weight": 0
              }
            ],
            "policy": {
              "overprovisioning_factor": 140
            }
          }
        }
      ],
      "dynamic_endpoint_configs": [
        {
          "endpoint_config": {

// The env var no longer exists afterwards
$ python main.py

Hello World from Python
```

</div>

!!! tip
    You can read more about it at <a href="https://12factor.net/config" class="external-link" target="_blank">The Twelve-Factor App: Config</a>.

### Types and validation

   */
  public long approximateElementCount() {
    long bitSize = bits.bitSize();
    long bitCount = bits.bitCount();

    /**
     * Each insertion is expected to reduce the # of clear bits by a factor of
     * `numHashFunctions/bitSize`. So, after n insertions, expected bitCount is `bitSize * (1 - (1 -
     * numHashFunctions/bitSize)^n)`. Solving that for n, and approximating `ln x` as `x - 1` when x

// 现在它可以读取环境变量

Hello Wade Wilson from Python

// 之后环境变量不再存在
$ python main.py

Hello World from Python
```

</div>

!!! tip
    您可以在 <a href="https://12factor.net/config" class="external-link" target="_blank">Twelve-Factor App: Config</a> 中阅读更多相关信息。

### 类型和验证

这些环境变量只能处理文本字符串，因为它们是外部于 Python 的，并且必须与其他程序和整个系统兼容（甚至与不同的操作系统，如 Linux、Windows、macOS）。

$ python main.py

Hello World from Python
```

</div>

!!! tip "Tipp"
    Weitere Informationen dazu finden Sie unter <a href="https://12factor.net/config" class="external-link" target="_blank">The Twelve-Factor App: Config</a>.

### Typen und Validierung

     *
     * <ul>
     *   <li>For an empty list, it is 1 (base case).
     *   <li>When r numbers are added to a list of n-r elements, the number of permutations is
     *       increased by a factor of (n choose r).
     * </ul>
     */
    private static <E> int calculateSize(
        List<E> sortedInputList, Comparator<? super E> comparator) {
      int permutations = 1;
      int n = 1;
      int r = 1;

	}

	return s, nil
}

// cleanup ".trash/" folder every 5m minutes with sufficient sleep cycles, between each
// deletes a dynamic sleeper is used with a factor of 10 ratio with max delay between
// deletes to be 2 seconds.
func (s *erasureSets) cleanupDeletedObjects(ctx context.Context) {
	timer := time.NewTimer(globalAPIConfig.getDeleteCleanupInterval())
	defer timer.Stop()