Meta-Comments

Sometimes you have boilerplate code that you'd like to insert/execute before or after the content of the live code block is executed. This is where meta-comments come in. Meta-comments are comments that are placed within the content of the code block and are used to split the code into preCode, code and postCode parts. pre- and post- code parts can not be changed by the user, but the code part can be edited by the user.

Here's an example of a code block with meta-comments:

```py live_py
from time import time
t0 = time()
### PRE
def fib(n):
    if n <= 1:
        return n
    return fib(n-1) + fib(n-2)
a_5 = fib(27)
### POST
t1 = time()
print(f'Time taken: {t1 - t0:.6f} seconds')
```

def fib(n):
    if n <= 1:
        return n
    return fib(n-1) + fib(n-2)
a_5 = fib(27)

Hover over the code block

Hover over the code block to see the buttons to expand preCode and postCode parts of the code block.