**FastAPI** will do the right thing with each, the same as with normal dependencies.

///

## A dependency with `yield` and `try` { #a-dependency-with-yield-and-try }

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

         * aftereffects and bogus error messages.
         */
        List<Dependency> dependencies = model.getDependencies();
        Map<String, Dependency> normalized = new LinkedHashMap<>(dependencies.size() * 2);

        for (Dependency dependency : dependencies) {
            normalized.put(dependency.getManagementKey(), dependency);
        }

        if (dependencies.size() != normalized.size()) {

  </scm>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t05-b</artifactId>
        <version>1.0</version>
      </dependency>
      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t05-d</artifactId>
        <version>1.0</version>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <dependencies>

    <dependencies>
      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t07-b</artifactId>
        <version>1.0</version>
      </dependency>
      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t07-d</artifactId>
        <version>1.0</version>
        <scope>test</scope>
        <optional>false</optional>
      </dependency>
    </dependencies>

  <dependencies>

    <dependency>
      <groupId>maven-test-compile</groupId>
      <artifactId>scope-default</artifactId>
      <version>1.0</version>
    </dependency>

    <dependency>
      <groupId>maven-test-compile</groupId>
      <artifactId>scope-test</artifactId>
      <version>1.0</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>maven-test-compile</groupId>

We can do better...

## What makes a dependency { #what-makes-a-dependency }

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

A "**callable**" in Python is anything that Python can "call" like a function.

  <dependencyManagement>

    <dependencies>

      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t04-a</artifactId>
        <version>1.0</version>
      </dependency>

      <dependency>
        <groupId>maven-test</groupId>
        <artifactId>t04-b</artifactId>
        <version>1.0</version>
      </dependency>

    <dependency>
      <groupId>maven-test</groupId>

  <description>Maven 4 API - Maven SPI.</description>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-annotations</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-model</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-api-core</artifactId>

          <version>2.1-SNAPSHOT</version>
          <dependencies>
            <dependency>
              <groupId>org.apache.maven.its.mng3906</groupId>
              <artifactId>e</artifactId>
              <version>0.1</version>
            </dependency>
            <dependency>
              <groupId>org.apache.maven.its.mng3906</groupId>
              <artifactId>a</artifactId>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>test</groupId>
                <artifactId>other</artifactId>
                <version>0.1-SNAPSHOT</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.junit</groupId>
                <artifactId>bom</artifactId>