如何在snakemake中处理配置文件中提供的ftp链接？

ftp_link: ftp://example.com/path/to/file.txt

rule some_rule:
    input:
        ...
    output:
        ...
    params:
        ftp_link=config["ftp_link"]
    shell:
        """
        some_command {params.ftp_link} ...
        """

from ftplib import FTP

# 解析ftp链接
ftp_link = "ftp://example.com/path/to/file.txt"
ftp_parts = ftp_link.split("/")
ftp_host = ftp_parts[2]  # example.com
ftp_path = "/".join(ftp_parts[3:])  # path/to/file.txt

# 连接到ftp服务器
ftp = FTP(ftp_host)
ftp.login()

# 下载文件
local_file = "file.txt"
with open(local_file, "wb") as f:
    ftp.retrbinary(f"RETR {ftp_path}", f.write)

# 关闭连接
ftp.quit()