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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_login_shell(proc_cmd):
 """Form shell information from the SHELL environment variable if possible. """

    login_shell = os.environ.get('SHELL', '')
    if login_shell:
        proc_cmd = login_shell
    else:
        proc_cmd = proc_cmd[1:]
    return (os.path.basename(proc_cmd).lower(), proc_cmd)