* and the arithmetic mean is always higher than the geometric mean.
     *
     * b) this iteration converges to floor(sqrt(x)). In fact, the number of correct digits doubles
     * with each iteration, so this algorithm takes O(log(digits)) iterations.
     *
     * We start out with a double-precision approximation, which may be higher or lower than the

  }

  /**
   * This test is for a case where two Service.Listener callbacks for the same service would call
   * transitionService in the wrong order due to a race. Due to the fact that it is a race this test
   * isn't guaranteed to expose the issue, but it is at least likely to become flaky if the race
   * sneaks back in, and in this case flaky means something is definitely wrong.
   *

### Create Models

Import `SQLModel` and create a database model:

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[1:11] hl[7:11] *}

The `Hero` class is very similar to a Pydantic model (in fact, underneath, it actually *is a Pydantic model*).

There are a few differences:

     * just to be safe.
     *
     * The real purpose of this test is to produce a TSAN failure if MapIteratorCache is unsafe for
     * reads from multiple threads -- unsafe, in fact, even in the absence of a concurrent write.
     * The specific problem we had was unsafe reads of lastEntryReturnedBySomeIterator. (To fix the
     * problem, we've since marked that field as volatile.)
     *

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. ✨

   * this range. Note that discrete ranges such as {@code (1..4)} and {@code [2..3]} are <b>not</b>
   * equal to one another, despite the fact that they each contain precisely the same set of values.
   * Similarly, empty ranges are not equal unless they have exactly the same representation, so
   * {@code [3..3)}, {@code (3..3]}, {@code (4..4]} are all unequal.
   */

  /**
   * Maximum parts (labels) in a domain name. This value arises from the 255-octet limit described
   * in <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11 with the fact that the
   * encoding of each part occupies at least two bytes (dot plus label externally, length byte plus
   * label internally). Thus, if all labels have the minimum size of one byte, 127 of them will fit.
   */

        }
        return toReturn;
      }

      @GuardedBy("lock")
      /*
       * The GuardedBy checker warns us that we're not holding cancellationDelegate.lock. But in
       * fact we are holding it because it is the same as this.lock, which we know we are holding,
       * thanks to @GuardedBy above. (cancellationDelegate.lock is initialized to this.lock in the
       * call to `new SupplantableFuture` below.)

    List<Integer> fromList = Lists.newLinkedList(SOME_SEQUENTIAL_LIST);
    List<String> list = transform(fromList, SOME_FUNCTION);
    assertTransformIterator(list);
  }

  /**
   * This test depends on the fact that {@code AbstractSequentialList.iterator} transforms the
   * {@code iterator()} call into a call on {@code listIterator(int)}. This is fine because the
   * behavior is clearly documented so it's not expected to change.
   */

    List<Integer> fromList = Lists.newLinkedList(SOME_SEQUENTIAL_LIST);
    List<String> list = transform(fromList, SOME_FUNCTION);
    assertTransformIterator(list);
  }

  /**
   * This test depends on the fact that {@code AbstractSequentialList.iterator} transforms the
   * {@code iterator()} call into a call on {@code listIterator(int)}. This is fine because the
   * behavior is clearly documented so it's not expected to change.
   */