How to define global variables in Python.

In Python, you can use the global keyword to define global variables. Here is an example code for defining a global variable:

# 定义一个全局变量
global_var = 10

def function():
    # 使用全局变量
    global global_var
    global_var += 5
    print(global_var)

function()  # 输出15

By using the global keyword inside a function, you declare a variable as a global variable, allowing you to modify the value of the global variable within the function. It is important to note that when modifying a global variable inside a function, the global keyword must be used to prevent the creation of a new local variable.