**FastAPI** is helemaal gebaseerd op deze type hints, ze geven veel voordelen.

Maar zelfs als je **FastAPI** nooit gebruikt, heb je er baat bij om er iets over te leren.

/// note

Als je een Python expert bent en alles al weet over type hints, sla dan dit hoofdstuk over.

///

## Motivatie

Laten we beginnen met een eenvoudig voorbeeld:

{* ../../docs_src/python_types/tutorial001.py *}

@NullUnmarked
public class BinaryTreeTraverserBenchmark {
  private static class BinaryNode {
    final int x;
    final Optional<BinaryNode> left;
    final Optional<BinaryNode> right;

    BinaryNode(int x, Optional<BinaryNode> left, Optional<BinaryNode> right) {
      this.x = x;
      this.left = left;
      this.right = right;
    }
  }

  enum Topology {
    BALANCED {
      @Override

.termynal-comment {
  color: #4a968f;
  font-style: italic;
  display: block;
}

.termy {
  /* For right to left languages */
  direction: ltr;
}

.termy [data-termynal] {
  white-space: pre-wrap;
}

.termy .linenos {
  display: none;
}

a.external-link {
  /* For right to left languages */
  direction: ltr;
  display: inline-block;
}

a.external-link::after {
  /* \00A0 is a non-breaking space

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Short[] concat(Short[] left, Short[] right) {
    Short[] result = new Short[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Long[] concat(Long[] left, Long[] right) {
    Long[] result = new Long[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Short[] concat(Short[] left, Short[] right) {
    Short[] result = new Short[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

     * method. It is an efficient relative that also will pad the left side so
     * that the result is <code>size</code> digits.
     *
     * @param val the integer value to convert to hexadecimal
     * @param size the desired length of the resulting hex string (will be left-padded with zeros)
     * @return a hexadecimal string representation of the value, padded to the specified size
     */

	if len(users1) != 3 {
		t.Errorf("should find two users using left join, but got %v", len(users1))
	}

	var users2 []User
	DB.Joins("inner join pets on pets.user_id = users.id AND pets.name = ?", user.Pets[0].Name).Where("users.name = ?", user.Name).First(&users2)
	if len(users2) != 1 {
		t.Errorf("should find one users using left join with conditions, but got %v", len(users2))
	}

	var users3 []User

:11}.order-sm-12{-ms-flex-order:12;order:12}.offset-sm-0{margin-left:0}.offset-sm-1{margin-left:8.333333%}.offset-sm-2{margin-left:16.666667%}.offset-sm-3{margin-left:25%}.offset-sm-4{margin-left:33.333333%}.offset-sm-5{margin-left:41.666667%}.offset-sm-6{margin-left:50%}.offset-sm-7{margin-left:58.333333%}.offset-sm-8{margin-left:66.666667%}.offset-sm-9{margin-left:75%}.offset-sm-10{margin-left:83.333333%}.offset-sm-11{margin-left:91.666667%}}@media (min-width:768px){.col-md{-ms-flex-preferred-...

			return err
		}
		// Subtract hash length..
		left -= int64(n)
		if left < shardSize {
			shardSize = left
		}

		read, err := io.CopyBuffer(h, io.LimitReader(r, shardSize), *bufp)
		if err != nil {
			// Read's failed for object with right size, at different offsets.
			return errFileCorrupt
		}

		left -= read
		if !bytes.Equal(h.Sum(nil), hashBuf[:n]) {
			return errFileCorrupt