// Step 1 is not cancelled because it was done.
    assertWithMessage("step1.statusFuture().isCancelled()")
        .that(step1.statusFuture().isCancelled())
        .isFalse();
    // But its closeable is closed.
    assertClosed(closeable1);

    // Step 2 is cancelled because it wasn't complete.
    assertWithMessage("step2.statusFuture().isCancelled()")
        .that(step2.statusFuture().isCancelled())
        .isTrue();

You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step { #recap-step-by-step }

### Step 1: import `FastAPI` { #step-1-import-fastapi }

{* ../../docs_src/first_steps/tutorial001.py hl[1] *}

`FastAPI` is a Python class that provides all the functionality for your API.

# Security - First Steps { #security-first-steps }

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

                  "text": "N/A"
                }
              },
              "type": "special"
            }
          ],
          "thresholds": {
            "mode": "percentage",
            "steps": [
              {
                "color": "green",
                "value": null
              }
            ]
          },
          "unit": "dtdurations"
        },
        "overrides": []
      },

        include:
          - os: windows-latest
            java: 21
            root-pom: pom.xml
    runs-on: ${{ matrix.os }}
    env:
      ROOT_POM: ${{ matrix.root-pom }}
    steps:
      # Cancel any previous runs for the same branch that are still running.
      - name: 'Cancel previous runs'
        uses: styfle/cancel-workflow-action@85880fa0301c86cca9da44039ee3bb12d3bedbfa # 0.12.1
        with:

                  "text": "N/A"
                }
              },
              "type": "special"
            }
          ],
          "thresholds": {
            "mode": "absolute",
            "steps": [
              {
                "color": "green",
                "value": null
              },
              {
                "color": "red",
                "value": 80
              }
            ]

 * is by declaring that step to be the last step of the pipeline. Nevertheless, we refer to the
 * "value" of a successful step or the "result" (value or exception) of any step.
 *
 * <ol>
 *   <li>A pipeline starts at its leaf step (or steps), which is created from either a callable
 *       block or a {@link ListenableFuture}.

jobs:
  changes:
    runs-on: ubuntu-latest
    # Required permissions
    permissions:
      pull-requests: read
    # Set job outputs to values from filter step
    outputs:
      docs: ${{ steps.filter.outputs.docs }}
    steps:
    - uses: actions/checkout@v5
    # For pull requests it's not necessary to checkout the code but for the main branch it is
    - uses: dorny/paths-filter@v3
      id: filter

    ///

    The `--upgrade` option tells `pip` to upgrade the packages if they are already installed.

    Because the previous step copying the file could be detected by the **Docker cache**, this step will also **use the Docker cache** when available.

 * is by declaring that step to be the last step of the pipeline. Nevertheless, we refer to the
 * "value" of a successful step or the "result" (value or exception) of any step.
 *
 * <ol>
 *   <li>A pipeline starts at its leaf step (or steps), which is created from either a callable
 *       block or a {@link ListenableFuture}.