But we want to be able to parameterize that fixed content.

## A "callable" instance { #a-callable-instance }

In Python there's a way to make an instance of a class a "callable".

Not the class itself (which is already a callable), but an instance of that class.

To do that, we declare a method `__call__`:

	wget -O /tmp/gopath/bin/docker-compose https://github.com/docker/compose/releases/download/${COMPOSE_VERSION}/docker-compose-linux-x86_64
	chmod +x /tmp/gopath/bin/docker-compose

	cleanup

	TAG=minio/minio:dev make docker

	MINIO_VERSION=RELEASE.2019-12-19T22-52-26Z docker-compose \
		-f "buildscripts/upgrade-tests/compose.yml" \
		up -d --build

	add_alias

	mc mb minio/minio-test/

func TestLoadOrStoreVisitMap(t *testing.T) {
	var vm visitMap
	var loaded bool
	type testM struct {
		Name string
	}

	t1 := testM{Name: "t1"}
	t2 := testM{Name: "t2"}
	t3 := testM{Name: "t3"}

	vm = make(visitMap)
	if loaded = loadOrStoreVisitMap(&vm, reflect.ValueOf(&t1)); loaded {
		t.Fatalf("loaded should be false")
	}

	if loaded = loadOrStoreVisitMap(&vm, reflect.ValueOf(&t1)); !loaded {

![Erasure](https://github.com/minio/minio/blob/master/docs/screenshots/erasure-code.jpg?raw=true)

## What is Bit Rot protection?

        // Modify the original raw array
        raw[0] = 0x05;

        // Ensure the AvPair's internal raw array is not affected (defensive copy not made)
        // This test assumes that the AvPair constructor does NOT make a defensive copy of the raw array.
        // If a defensive copy were made, this test would fail, and the behavior would be more robust.

{* ../../docs_src/response_cookies/tutorial001.py hl[10:12] *}

/// tip

Keep in mind that if you return a response directly instead of using the `Response` parameter, FastAPI will return it directly.

So, you will have to make sure your data is of the correct type. E.g. it is compatible with JSON, if you are returning a `JSONResponse`.

And also that you are not sending any data that should have been filtered by a `response_model`.

///

### 5. Setup MinIO with OpenID configuration URL

MinIO server expects environment variable for OpenID configuration url as `MINIO_IDENTITY_OPENID_CONFIG_URL`, this environment variable takes a single entry.

```
export MINIO_IDENTITY_OPENID_CONFIG_URL=https://localhost:9443/oauth2/oidcdiscovery/.well-known/openid-configuration
export MINIO_IDENTITY_OPENID_CLIENT_ID="843351d4-1080-11ea-aa20-271ecba3924a"

| `minio_cluster_usage_version_total`          | Total number of versions (includes delete marker) in a cluster |
| `minio_cluster_usage_deletemarker_total`     | Total number of delete markers in a cluster                    |
| `minio_cluster_bucket_total`                 | Total number of buckets in the cluster                         |

## Cluster Drive Metrics

      long hash1 = lowerEight(bytes);
      long hash2 = upperEight(bytes);

      boolean bitsChanged = false;
      long combinedHash = hash1;
      for (int i = 0; i < numHashFunctions; i++) {
        // Make the combined hash positive and indexable
        bitsChanged |= bits.set((combinedHash & Long.MAX_VALUE) % bitSize);
        combinedHash += hash2;
      }
      return bitsChanged;
    }

    @Override

- In this algorithm, we also make sure that we spread the drives out evenly. MinIO server expands ellipses passed as arguments. Here is a sample expansion to demonstrate the process.

```
minio server http://host{1...2}/export{1...8}
```