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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 _ctl_cmd(cmd, name, conf_file, bin_env):
    '''
    Return the command list to use
    '''
    ret = [_get_supervisorctl_bin(bin_env)]
    if conf_file is not None:
        ret += ['-c', conf_file]
    ret.append(cmd)
    if name:
        ret.append(name)
    return ret