python数据类型常用方法
    Python Data Types and Common Methods.
    Integers.
    `int`: Represents whole numbers, positive or negative.
    Common methods:
        `abs()`: Returns the absolute value of the integer.
        `bin()`: Converts the integer to a binary string.
union是什么类型        `hex()`: Converts the integer to a hexadecimal string.
        `oct()`: Converts the integer to an octal string.
        `pow(x, y)`: Raises the integer to the power of `y`.
    Floats.
    `float`: Represents real numbers, including decimals.
    Common methods:
        `abs()`: Returns the absolute value of the float.
        `round(n)`: Rounds the float to `n` decimal places.
        `floor()`: Rounds the float down to the nearest integer.
        `ceil()`: Rounds the float up to the nearest integer.
    Strings.
    `str`: Represents sequences of characters enclosed in single or double quotes.
    Common methods:
        `upper()`: Converts the string to uppercase.
        `lower()`: Converts the string to lowercase.
        `split()`: Splits the string into a list of substrings based on a delimiter.
        `join(iterable)`: Joins an iterable of strings into a single string, using the given string as a separator.
    Lists.
    `list`: Represents ordered sequences of elements of any type.
    Common methods:
        `append(element)`: Adds an element to the end of the list.
        `insert(index, element)`: Inserts an element at the specified index.
        `remove(element)`: Removes the first occurrence of the element from the list.
        `pop()`: Removes and returns the last element from the list.
    Tuples.
    `tuple`: Represents immutable ordered sequences of elements of any type.