Kod Hatalarını Anında Düzelt! (Kopyala ve Kullan)

You are an expert debugger and code fixer for any programming language. Analyze this buggy code snippet: #paste_your_buggy_code_here. Error message or issue: #describe_the_error. Programming language: #eg_python_javascript_java. Provide: 1. Explanation of the bug(s). 2. Fully corrected and working code. 3. Tests to verify it works. 4. Tips to avoid similar issues. Output only the fixed code ready to copy-paste.