gdb-python: why below code is not working under gdb?

below code is working fine as a python code(without gdb module), but it is not working inside gdb?

#!/usr/bin/env python
import csv
import gdb

list = []
x = open("file.txt")
with x as csv_data:
    entries = csv.reader(csv_data, delimiter=",")
    for entry in entries:
        list.append({
            "name": entry[0],
            "type": entry[1],
            "link": entry[2],
            "level": entry[3]
        })

the error is :

(gdb) source script.py
 File "script.py", line 6
   with x as csv_data:
        ^
 SyntaxError: invalid syntax

file.txt is:

Mac, char, list, one
John, char, list, three
...
...

It seems there is issue with with and as keyword.