Have to throw out that disclosure ð. While there are a number of essential oils you can use for minor migraines and head pain, two of the top single oils are Peppermint and Lavender. Peppermint is effective for helping to relieve minor symptoms of those mind-numbing headaches that come from a variety of culprits.
An abstract class is like a class, but differs in that it only defines generic methods in the class, but does not actually implement them. Those methods will be implemented later by specialized sub-classes. This is how we get interfaces - interfaces are the implementation of the abstract class.
In Object Oriented Programming, an Interface is a description of all functions that an object must have in order to be an X. Again, as an example, anything that ACTS LIKE a light, should have a turn_on() method and a turn_off() method.