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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 listen_fds(unset_environment=True):
 """Return a list of socket activated descriptors Example:: (in primary window) $ systemd-activate -l 2000 python3 -c \\ 'from systemd.daemon import listen_fds; print(listen_fds())' (in another window) $ telnet localhost 2000 (in primary window) [3] """

    num = _listen_fds(unset_environment)
    return list(range(LISTEN_FDS_START, LISTEN_FDS_START + num))