Can someone explain to me how `deserialize` works in `input` of `transformer`?

export interface DataTransformer {
  serialize(object: any): any;
  deserialize(object: any): any;
}

interface InputDataTransformer extends DataTransformer {
  /**
   * This function runs **on the client** before sending the data to the server.
   */
  serialize(object: any): any;
  /**
   * This function runs **on the server** to transform the data before it is passed to the resolver
   */
  deserialize(object: any): any;
}

interface OutputDataTransformer extends DataTransformer {
  /**
   * This function runs **on the server** before sending the data to the client.
   */
  serialize(object: any): any;
  /**
   * This function runs **only on the client** to transform the data sent from the server.
   */
  deserialize(object: any): any;
}

export interface CombinedDataTransformer {
  /**
   * Specify how the data sent from the client to the server should be transformed.
   */
  input: InputDataTransformer;
  /**
   * Specify how the data sent from the server to the client should be transformed.
   */
  output: OutputDataTransformer;
}

...
  /**
   * This function runs **on the server** to transform the data before it is passed to the resolver
   */
  deserialize(object: any): any;
...