## Standard library {#library}...

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### Just Modern Python { #just-modern-python }

It's all based on standard **Python type** declarations (thanks to Pydantic). No new syntax to learn. Just standard modern Python.

If you need a 2 minute refresher of how to use Python types (even if you don't use FastAPI), check the short tutorial: [Python Types](python-types.md){.internal-link target=_blank}.

You write standard Python with types:

```Python
from datetime import date

Cache Miss will be typical if the item has not been read from the network, is uncacheable, or is past it's 
lifetime based on Response cache headers.

 - CallStart 
 - **CacheMiss**
 - ProxySelectStart
 - ... Standard Events ...
 - CallEnd
        
### Conditional Cache Hit
 
When cache flags require checking the cache results are still valid an early cacheConditionalHit event is

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///

## Automatic conversion { #automatic-conversion }

`Header` has a little extra functionality on top of what `Path`, `Query` and `Cookie` provide.

Most of the standard headers are separated by a "hyphen" character, also known as the "minus symbol" (`-`).

But a variable like `user-agent` is invalid in Python.

For now, you just need to know that `Annotated` exists, and that it's standard Python. 😎

Later you will see how **powerful** it can be.

/// tip

The fact that this is **standard Python** means that you will still get the **best possible developer experience** in your editor, with the tools you use to analyze and refactor your code, etc. ✨

                    return new StandardImplForwardingSet<>(new LinkedHashSet<>(asList(elements)));
                  }
                })
            .named("ForwardingSet[LinkedHashSet] with standard implementations")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.ALLOWS_NULL_VALUES,
                CollectionFeature.GENERAL_PURPOSE)
            .createTestSuite());

	ARN          string
	// EncryptionConfiguration TODO: not needed for MinIO
}

func (d Destination) isValidStorageClass() bool {
	if d.StorageClass == "" {
		return true
	}
	return d.StorageClass == "STANDARD" || d.StorageClass == "REDUCED_REDUNDANCY"
}

// IsValid - checks whether Destination is valid or not.
func (d Destination) IsValid() bool {
	return d.Bucket != "" || !d.isValidStorageClass()
}

                    return new StandardImplForwardingSet<>(new LinkedHashSet<>(asList(elements)));
                  }
                })
            .named("ForwardingSet[LinkedHashSet] with standard implementations")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.ALLOWS_NULL_VALUES,
                CollectionFeature.GENERAL_PURPOSE)
            .createTestSuite());