6.18 math 6.19 multiprocessing 6.20 nntplib 6.21 os 6.22 pathlib 6.23 pdb On Windows now$_{Pdb}$ supports$_{~/.pdbrc}$ . (Contributed by Tim Hopper and Dan Lidral-Porter in bpo-20523.) Added$_{pathlib.Path.readlink()}$ which acts similarly to$_{os.readlink()}$ . (Contributed by Girts Folk- manis in bpo-30618) Added$_{os.waitstatus_to_exitcode()}$ function: convert a wait status to an exit code. (Contributed by Victor Stinner in bpo-40094.) The$_{os.putenv()}$ and$_{os.unsetenv()}$ functions are now always available. (Contributed by Victor Stinner in bpo-39395.) The$_{os.unsetenv()}$ function is now also available on Windows. (Contributed by Victor Stinner in bpo-39413.) Exposed the Linux-specific$_{os.pidfd_open()}$ (bpo-38692) and$_{os.P_PIDFD}$ (bpo-38713) for process man- agement with file descriptors. Added$_{CLD_KILLED}$ and$_{CLD_STOPPED}$ for$_{si_code}$. (Contributed by Dong-hee Na in bpo-38493.) NNTP and$_{NNTP_SSL}$ now raise a$_{ValueError}$if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. (Contributed by Dong-hee Na in bpo-39259.) The multiprocessing.SimpleQueue class has a new close() method to explicitly close the queue. (Con- tributed by Victor Stinner in bpo-30966.) Added math.ulp() : return the value of the least significant bit of a float. (Contributed by Victor Stinner in bpo-39310.) Added$_{math.nextafter()}$ : return the next floating-point value after x towards y . (Contributed by Victor Stinner in bpo-39288.) Added$_{math.lcm()}$ : return the least common multiple of specified arguments. (Contributed by Mark Dickinson, Ananthakrishnan and Serhiy Storchaka in bpo-39479 and bpo-39648.) Expanded the$_{math.gcd()}$ function to handle multiple arguments. Formerly, it only supported two arguments. (Contributed by Serhiy Storchaka in bpo-39648.) 10