How is the raise statement used in Python?

In Python, the raise keyword is used to manually trigger an exception. It can be used to raise a specific type of exception and also provide custom exception information. The basic syntax format for raise is as follows:

raise ExceptionType("Error message")

ExceptionType is the type of the exception, which can be a built-in Python exception type (such as ValueError, TypeError, etc.) or a custom exception type; while “Error message” is an optional custom error message used to describe the specific situation of the exception.

For example, the following code example demonstrates how to use raise to raise a ValueError exception.

x = -1
if x < 0:
    raise ValueError("Value must be greater than or equal to 0")

In practical applications, “raise” is typically used in combination with try-except statements to capture and handle exceptions. By raising an exception in the try block and then handling it in the except block, a more flexible control flow for exception handling can be achieved.