The Cell pattern

We have already learned that reactive programming is all about processing values that vary over time. The reactive programming model is centered on the notion of Observables. There are two variants of Observables, which are as follows:

• Cells: A cell is an entity (a variable, or a memory location) where values are regularly updated over time. They are also called properties or behaviors, in some contexts.
• Streams: A stream represents a series of events. They are data that is often associated with actions. When people think of Observables, they have got stream variant of Observables in their mind.

We will implement a toy version of a Cell programming pattern. We will only focus on implementing basic functionality. The code needs tidying up for production use.

The following implementation can be optimized, if we are implementing a a controller class called Cell controller. . Then, the Cell controller class ( which contains a single Rx Subject for all cells)  can receive notifications...