Python Revision Tour

Lesson

Part 1 — the building blocks: tokens, data types, operators, expressions and flow of control.

In this lesson you will

Identify tokens and data types, and tell mutable types from immutable ones
Evaluate expressions using operator precedence, true and floor division and type conversion
Trace and write programs with if, elif, else, for, while, break and continue

Part 1 at a glance

Concept

Tokens: the smallest units

Python reads a program as a stream of tokens.

Table of the five kinds of tokens: keywords such as if and while, identifiers such as total_fee, literals such as 25 and Pune, operators such as plus and floor division, and punctuators such as brackets, colon and comma
Token	What it is	Examples
Keyword	Reserved word with a fixed meaning	`if`, `for`, `while`, `True`, `None`
Identifier	Name chosen by the programmer	`total_fee`, `_count`, `marks2`
Literal	A fixed value written in the code	`25`, `3.75`, `"Pune"`, `True`
Operator	Symbol that acts on values	`+`, `//`, `**`, `==`, `and`, `in`
Punctuator	Symbol that organises code	`( )`, `[ ]`, `{ }`, `:`, `,`

Concept

Every value has a type. A mutable object can be changed in place; an immutable one cannot.