None
None is Python’s singleton object representing the absence of a value or meaningful result.
Get Programming: Learn to code with Python
None is Python's special singleton value representing the absence of a value.
- How it is used
- Marks an absent value and represents the result of a function that omits a return statement.
- How deep it goes
- Explains None’s type, distinguishes it from "None", and traces its appearance when functions print or return values.
- Examples
- Uses an unnamed pet, type-identification checks, and say_name/show_kid calls to demonstrate absent values and implicit returns.
- What you can do after
- Evaluate/understand whether a function prints a value, returns a value, or supplies None automatically.
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Python How-To
None is Python's singleton value representing the absence of a meaningful result or value.
- How it is used
- Uses None to initialize a possibly unsuccessful search, provide a safe mutable-parameter default, and identify an implicit function return.
- How deep it goes
- Works through missing matches, shared mutable defaults, and implicit returns without examining None’s implementation.
- Examples
- Shows an urgent-task search, a task-grouping function with a None default, and a list-appending function that implicitly returns None.
- What you can do after
- Apply it to handle an absent search result, avoid shared mutable defaults, and recognize an implicit function return.
The Quick Python Book, Fourth Edition
None is Python's singleton object representing the absence of a value.
- How it is used
- Represents absence, deferred data, invalid values, and the default result of functions without an explicit return.
- How deep it goes
- Explains singleton behavior, Boolean falsiness, implicit returns, placeholders, and exception-based invalid-value handling.
- Examples
- Uses functions without return statements, invalid spreadsheet cells, cell conversion, and safe formula application.
- What you can do after
- Apply None as a placeholder, recognize implicit function results, and handle invalid values during spreadsheet-style evaluation.
Read how The Quick Python Book, Fourth Edition explains None →
Tiny Python Projects: Learn coding and testing with puzzles and games
None is Python's singleton value representing the absence of a meaningful value.
- How it is used
- Uses None to signal an absent input, missing function result, or intentionally non-returning in-place operation.
- How deep it goes
- Explains None through list mutation, randomization, omitted arguments, and implicit returns, without descending into object internals.
- Examples
- Demonstrates None with list.sort(), random.shuffle(), omitted argparse inputs, and a Tic-Tac-Toe winner search.
- What you can do after
- Diagnose accidental None assignments and interpret None as a deliberate absence signal in command-line programs and functions.
Read how Tiny Python Projects: Learn coding and testing with puzzles and games explains None →
Related concepts
- dict.getproduced by · dict.get is a Python dictionary method that returns the value for a key or a specified default when the key is absent.
- NoneTypekind of · NoneType is the Python type of the singleton value None, which represents the absence of a value.
- return statementproduced by · A return statement ends the current function or routine invocation and optionally supplies its result to the caller.
- default valueconfigured by · A default value is a predefined or automatically supplied value used when an expected input, argument, field, or configuration setting is omitted or unspecified.
- similarity searchproduced by · Similarity search is a retrieval technique that finds or ranks items by comparing their representations with a query according to a similarity or distance measure.
- functionproduced by · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
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