用变量打开Python文件

我是python的初学者。在下面的代码中，为什么在打开文件和其他位置时使用变量“env”。从教程中，我看到文件打开格式总是像open（filename）一样作为f，但这里使用了一个变量名。请解释一下

def main():
    global debug, testing,env, mode
    newID=0
    rv=[]
    name=''

    if "debug" in sys.argv:
        debug = True
    if "testing" in sys.argv:
        testing = True
    if debug:
        print(sys.argv)

    if "copyAccountProfile" in sys.argv:
        mode = 'copyAccountProfile' 

    envProfile = sys.argv[1]
 
    if debug:
        print(envProfile)

    with open(envProfile) as f_in: 
        lineList = list(line for line in (l.strip() for l in f_in) if line)
#    ff = open(envProfile)
#    lineList = [line for line in ff.readlines() if line.strip()]
    for line in lineList:
        if line.startswith('#'):
            continue
        [nm, v]=line.strip().split('=')
        env[nm.strip()]=v.strip()
        if debug:
            print(env)

    with open(env['accountProfile']) as f_in: 
        accountList = list(line for line in (l.strip() for l in f_in) if line)
    if mode == 'copyData':  
        for acc in accountList:
            [name,Id] = acc.strip().split(',')
            name = name.strip()
            #copyData(name, env['src_ror'], workingDir, env['dst_ror'], workingDir, 'bk_files', True)         
            copyData(name, env['src_ror'], workingDir, env['dst_ror'], workingDir, 'bk_files')         
            copyData(name, env['src_ror'], workingDir, env['dst_bpm'], backupDir, 'bk_files')         
            copyData(name, env['src_bpm'], workingDir, env['dst_bpm'], workingDir, 'ft_files')         
            localCopyData(name, env['dst_bpm'], workingDir, backupDir) 
    else:
    #copy updated accountProfile from dst_ror to dst_bpm
        fname = env['accountProfile']
        # src = ip:port, dst = ip:port}
        [sIp, sPort]=env['dst_ror'].split(':')
        [dIp, dPort]=env['dst_bpm'].split(':')
        copyFile(fname, sIp, sPort, toolDir, dPort, dIp, toolDir) 
    

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欢迎普雷马。变量名可以是作者希望的任何名称。通常，程序员应该使用与存储在该变量中的数据相关的描述性变量名

由于这个示例的文档记录得很差，我不得不假设作者使用了“env”来表示这个变量以某种方式连接到某个环境

作者似乎在使用“f_in”变量名来表示该文件是一个输入文件