Update a document in DynamoDB, with a key to identify the
            document, and using the specified config.
            
 Declaration Syntax
 Declaration Syntax| C# | 
public Document UpdateItem( Document doc, IDictionary<string, DynamoDBEntry> key, UpdateItemOperationConfig config )
 Parameters
 Parameters- doc (Document)
- Attributes to update.
- key (IDictionary<(Of <(<'String, DynamoDBEntry>)>)>)
- Key of the document.
- config (UpdateItemOperationConfig)
- Configuration to use.
 Return Value
 Return ValueNull or updated attributes, depending on config.
 See Also
 See Also