title: Create pydantic model for Optional field with alias
body: <p>Pydantic model for compulsory field with alias is created as follows</p>
  <pre><code>class MedicalFolderUpdate(RWModel):
      id : str = Field(alias='_id')
      university : Optional[str]
  </code></pre>
  <p>How to add optional field university's alias name 'school' as like of id?</p>