Off topic:python3 click syntax error, please help

Question

[phoenixice154]

I am trying to develop a python3 script using the click module to pass the arguments from commandline to variables in the script. my python3 version is 3.8.3 on a ubuntu 20.04 desktop.

The file is listed as following:

---

#!/usr/bin/env python3

# -*- coding: utf-8 -*-

import click

@click.command()

@click.option('--bam', '-b',  multiple=True, type=string, hide_input=False, required=True, help="BAM input")

@click.option('--threads', '-t', default=1, nargs=1, type=int, hide_input=False, required=False, help="Number of threads")

@click.option('--out', '-o', default="MyOut.stats", nargs=1, type=string, hide_input=False, required=False, help="Statistics Output")


debug_mode = 0

---

When I run it, I got a syntax error:

File "****/alignment_stats.py", line 12

    debug_mode = 0

    ^

SyntaxError: invalid syntax

It seems the error locates at the line '@click.command()', but I can not figure it out why?

I am familiar with perl, but quite new to python3. If anyone knows the answer, please help.