1.4 Variables

Assignment statement
Variables allow programs to refer to values using names rather than memory locations. Ex: age refers to a person’s age, and birth refers to a person’s date of birth.
A statement can set a variable to a value using the assignment operator (=). Note that this is different from the equal sign of mathematics. Ex: age = 6 or birth = “May 15”. The left side of the assignment statement is a variable, and the right side is the value the variable is assigned.

Variable naming rules
A variable name can consist of letters, digits, and underscores and be of any length. The name cannot start with a digit. Ex: 101class is invalid. Also, letter case matters. Ex: Total is different from total. Python’s style guide recommends writing variable names in snake case, which is all lowercase with underscores in between each word, such as first_name or total_price.

A name should be short and descriptive, so words are preferred over single characters in programs for readability. Ex: A variable named count indicates the variable’s purpose better than a variable named c.
Python has reserved words, known as keywords, which have special functions and cannot be used as names for variables (or other objects).

Falseawaitelseimportpass
Nonebreakexceptinraise
Trueclassfinallyisreturn
andcontinueforlambdatry
asdeffromnonlocalwhile
assertdelglobalnotwith
asynchelififoryield

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