---
id: python-none
title: "Python None"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["NoneType", "파이썬 None"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["python", "programming", "w3schools", "none", "nonetype"]
raw_sources: ["https://www.w3schools.com/python/python_none.asp"]
applied_in: []
github_commit: ""
---

# [[Python None]]

## 🎯 한 줄 통찰 (One-line insight)
None is the sole instance of its own type (NoneType), evaluates to False in a boolean context, and should be compared with `is`/`is not` (identity) rather than `==`/`!=` (equality). [S1]

## 🧠 핵심 개념 (Core concepts)
- **`None`** — a special constant representing the absence of a value; data type `NoneType`. [S1]
- **Single instance** — None is the only instance of NoneType. [S1]
- **Comparison** — use `is` / `is not`, not `==`/`!=`, to check for None. [S1]
- **Falsy** — `bool(None)` is False. [S1]
- **Default function return** — a function with no explicit `return` returns None. [S1]

## 📖 세부 내용 (Details)
- Assign and check type: `x = None; print(type(x))  # <class 'NoneType'>`. [S1]
- Identity comparison: `if result is None: print("No result yet") else: print("Result is ready")`. [S1]
- Truthiness: `print(bool(None))  # False`. [S1]
- Implicit None return: `def myfunc(): x = 5; x = myfunc(); print(x)  # None`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — Python Functions 챕터에서 이미 예고된 "return 없으면 None"이 여기서 정식으로 다뤄진다. [S1]

## 💻 코드 패턴 (Code patterns)
Identity comparison with None (Python):
```python
result = None
if result is None:
    print("No result yet")
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[Python Tutorial]]
- **관련 개념:** [[Python Functions]], [[Python Operators Identity]], [[Python Booleans]]
- **참조 맥락:** "값 없음"을 표현하는 표준 상수 — is/is not 비교 규칙이 핵심.

## 📚 출처 (Sources)
- [S1] W3Schools — Python None — https://www.w3schools.com/python/python_none.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "Python None" page (Astra wiki-curation, P-Reinforce v3.1 format).