PYTHON IDENTIFIERS
A Python identifier is the name of a variable, function, class, module, or other Python object, and a valid identifier conforms to the following rules:
•It starts with a letter A to Z, a to z, or an underscore (_)
•It includes zero or more letters, underscores, and digits (0 to 9)
NOTE
Python identifiers cannot contain characters such as @, $, and %.
Python is a case-sensitive language, so Abc and abc different identifiers in Python.
In addition, Python has the following naming convention:
•Class names start with an uppercase letter and all other identifiers with a lowercase letter
•An initial underscore is used for private identifiers
•Two initial underscores are used for strongly private identifiers
A Python identifier with two initial underscore and two trailing underscore characters indicates a language-defined special name.
