title: Sequelize "model.associate" property doesn't work anymore?
body: <p>I'm using sequelize v5.21 and sequelize-cli v5.5.1 for a MySQL database.</p>
  
  <p>I'm currently trying to create some association 1:M under the following model generated code from the cli like so:</p>
  
  <p>Where: a is the source and b the target.</p>
  
  <pre><code>model.associate = function (models) {
  // associations can be defined here
   a.hasOne(models.b);
  }
  </code></pre>
  
  <p>and the other model, i have:</p>
  
  <pre><code>model.associate = function (models) {
  // associations can be defined here
   b.belongsTo(models.a);
  }
  </code></pre>
  
  <p>Finally, im using this code to check the associations by creating a entries:</p>
  
  <pre><code>    a.create({
    ...
    }).then(a =&gt; {
       return a.createB({
        ...,
      }).catch(err =&gt; console.log(err));
     }).catch(err =&gt; console.log(err)
     );
  </code></pre>
  
  <p>In which i'm getting an error on the "a.createB()..." as is not a function...</p>
  
  <p>So, i was curious enough and tried doing the associations right before checking the associations like so:</p>
  
  <pre><code>a.hasOne(b);
  b.belongsTo(a);
  </code></pre>
  
  <p>In which works just fine...</p>
  
  <p>My question is, is the "model.associate" property still working on the v5^?</p>
  
  <p>Note: I have used the check associations method provided in the sequelize documentation but i prefer this one since it's easier to read.</p>