Keras Models API

 Keras Models API provides three ways to create models.

• Sequential Model - the simple model - consists of layers. applied in succession.  You can create a Sequential model by passing a list of layers to the constructor of Sequential.
• The alternative, and preferred method for most use cases, is the Functional API. which is more flexible than the keras.Sequential API.  It enables the building of graphs of Layers.
• Model subclassing is building from scratch. for out of the box use cases.