Data Science

The scope chain of a function is constructed when a function is defined
Implying, a scope chain is a property of a function
The scope chain never changes throughout a program
A scope chain is used for variable lookups
Roughly, a scope chain is a list of objects
These objects consist of:
- Its own variables
- Its parent variables
A scope chain is considered a chain because each child scope has access to its parent scope
In other words, each scope is a list that is a chain of objects

Refer to the example below,
x can be accessed from anywhere
Implying, x is considered to be in the outer scope
More specifically, x is considered to be in the global scope
On the other hand, y is considered to be in the local scope of the function a()
Specifically, y can be accessed by the code in a() only

>>> x = 1

>>> def a():
...     y = 2

An execution context is separate from the scope chain
It is constructed when a function is invoked
An execution context is composed of the following:
- The function's parameters
- And local variables
- A reference to the scope chain
- The value of self
Roughly, an execution context is the environment of a function
An execution context refers to its scope chain for variable lookups
An execution context represents the execution of a function (or context)

The call stack is a collection of execution contexts
The bottom of the call stack contains the global execution context
Each time a new function is called, it gets placed on the top of the call stack
Once the execution of a function is finished, its execution context gets popped off the call stack
A call stack is used for tracking each execution context

Conceptually, an execution context is a stack of logical contexts
A logical context is a mapping of context variables to their values in that particular logical context
A context variable is an object representing a value in the execution context
A new context variable is created by calling:

>>> contextvars.ContextVar(name)

Here, name is the given name for the context variable
A new ContextVar(name) has the following methods:
- get(): A function for getting a context variable
- set(): A function for setting the value of a context variable
- delete(): A function for removing a context variable

Awaitables

Event Loop