**FastAPI** provides a convenience tool to structure your application while keeping all the flexibility.

/// info

If you come from Flask, this would be the equivalent of Flask's Blueprints.

///

## An example file structure { #an-example-file-structure }

Let's say you have a file structure like this:

```
.
├── app
│   ├── __init__.py
│   ├── main.py

  }

  /**
   * Returns a predicate that evaluates to {@code true} if the {@code CharSequence} being tested
   * contains any match for the given regular expression pattern. The test used is equivalent to
   * {@code Pattern.compile(pattern).matcher(arg).find()}
   *
   * @throws IllegalArgumentException if the pattern is invalid
   * @since 3.0
   */

            throw new IllegalStateException("Authenticator has been closed");
        }
    }

    /**
     * Return the domain and username in the format:
     * <code>domain\\username</code>. This is equivalent to <code>toString()</code>.
     */
    @Override
    public String getName() {
        boolean d = this.domain != null && this.domain.length() > 0;

    checkEntryNotNull(key, value);
    return new AbstractMap.SimpleImmutableEntry<>(key, value);
  }

  /**
   * Returns a new builder. The generated builder is equivalent to the builder created by the {@link
   * Builder} constructor.
   */
  public static <K, V> Builder<K, V> builder() {
    return new Builder<>();
  }

  /**

    /**
     * Returns {@code true} if there is at least one problem collected with severity equal or more severe than
     * {@link org.apache.maven.api.services.BuilderProblem.Severity#WARNING}. This check is logically equivalent
     * to "is there any problem reported?", given warning is the lowest severity.
     */
    default boolean hasWarningProblems() {
        return hasProblemsFor(BuilderProblem.Severity.WARNING);
    }

    /**

    }
    return String.valueOf(newChars);
  }

  /**
   * If the argument is an {@linkplain #isUpperCase(char) uppercase ASCII character}, returns the
   * lowercase equivalent. Otherwise returns the argument.
   */
  public static char toLowerCase(char c) {
    return isUpperCase(c) ? (char) (c ^ CASE_MASK) : c;
  }

  /**

   */
  public abstract ContiguousSet<C> intersection(ContiguousSet<C> other);

  /**
   * Returns a range, closed on both ends, whose endpoints are the minimum and maximum values
   * contained in this set. This is equivalent to {@code range(CLOSED, CLOSED)}.
   *
   * @throws NoSuchElementException if this set is empty
   */
  public abstract Range<C> range();

  /**

  override fun toString(): String = path.joinToString(separator = " / ")

  companion object {
    /**
     * A synthetic value that indicates there's no more bytes. Values with equivalent data may also
     * show up in ASN.1 streams to also indicate the end of SEQUENCE, SET or other constructed
     * value.
     */
    private val END_OF_DATA =
      DerHeader(

      dst[offset + i] = get(i);
    }
    return offset + size;
  }

  /**
   * Returns a view of this immutable list in reverse order. For example, {@code ImmutableList.of(1,
   * 2, 3).reverse()} is equivalent to {@code ImmutableList.of(3, 2, 1)}.
   *
   * @return a view of this immutable list in reverse order
   * @since 7.0
   */
  public ImmutableList<E> reverse() {

JetBrains [is working on][kotlin_sams] SAM conversions of Kotlin interfaces. Expect it in a future
release of the Kotlin language.


Companion Imports
-----------------

The equivalent of static methods in Java is companion object functions in Kotlin. The bytecode is
the same but `.kt` files now need `Companion` in the import.

This works with OkHttp 3.x:

```kotlin