When handling multiple pieces of data together in Python, a "list" is a very convenient data type. You can store various data such as usernames, tasks, or scores, like ["sato", "suzuki", "tanaka"].

The len() function is a built-in function in Python, meaning it's readily available without needing to import any external modules. Its primary purpose is to return the number of items in an object.

When working with dataframes in Python and pandas, there are many situations where you want to quickly check, "How many rows does this data have in total?" Understanding the number of rows is ...