await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

  @CanIgnoreReturnValue
  boolean addNode(N node);

  /**
   * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present, and sets
   * a value for that edge to {@code value} (overwriting the existing value, if any).
   *
   * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
   * undirected.
   *
   * <p>Values do not have to be unique. However, values must be non-null.
   *

                SuggestItem.Kind.DOCUMENT);

        Map<String, Object> existing = new HashMap<>();
        existing.put(FieldNames.DOC_FREQ, 5L);
        existing.put(FieldNames.QUERY_FREQ, 3L);
        existing.put(FieldNames.TIMESTAMP, System.currentTimeMillis());

        Map<String, Object> updated = SuggestItemSerializer.toUpdatedSource(item, existing);

        assertNotNull(updated);

                });
                form.crudMode = CrudMode.CREATE;
            });
        });
    }

    /**
     * Displays the form for editing an existing web crawler configuration.
     *
     * @param form the edit form containing web config ID
     * @return HTML response for the web config edit form
     */
    @Execute
    @Secured({ ROLE })

    builder.addEscape(' ', "_");
    Escaper first = builder.build();
    // Modify one of the existing mappings before creating a new escaper.
    builder.addEscape(' ', "-");
    builder.addEscape('!', "$");
    Escaper second = builder.build();
    // This should have no effect on existing escapers.
    builder.addEscape(' ', "*");

    // Test both escapers after modifying the builder.

            form.doc = fessConfig.convertToEditableDoc(entity);
        });
        currentForm = form;
        return asEditHtml();
    }

    /**
     * Displays the form for editing an existing document.
     *
     * @param form the edit form containing document ID
     * @return HTML response for the document edit form
     */
    @Execute
    @Secured({ ROLE })

    public void test_update() throws Exception {
        writeTestFile("a,b => c\nd,e => f\n");

        // Get existing item
        OptionalEntity<CharMappingItem> existing = charMappingFile.get(1L);
        assertTrue(existing.isPresent());

        // Update the item
        CharMappingItem updateItem = existing.get();
        updateItem.setNewInputs(new String[] { "m", "n" });
        updateItem.setNewOutput("o");

    builder.addEscape(' ', "_");
    Escaper first = builder.build();
    // Modify one of the existing mappings before creating a new escaper.
    builder.addEscape(' ', "-");
    builder.addEscape('!', "$");
    Escaper second = builder.build();
    // This should have no effect on existing escapers.
    builder.addEscape(' ', "*");

    // Test both escapers after modifying the builder.

        // Should not throw exception
    }

    // Test addFieldLog with existing field
    @Test
    public void test_addFieldLog_existingField() {
        Map<String, List<String>> fieldLogMap = new HashMap<>();
        List<String> existingList = new ArrayList<>();
        existingList.add("existing");
        fieldLogMap.put("field", existingList);

        return item;
    }

    /**
     * Creates an updated source map by merging the item with existing source.
     *
     * @param item The SuggestItem with new data
     * @param existingSource The existing source map from OpenSearch
     * @return A merged source map
     */