## 6.18 math 

Expanded the$_{math.gcd()}$ function to handle multiple arguments. Formerly, it only supported two arguments. (Contributed by Serhiy Storchaka in bpo-39648.) 

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.) 

Added$_{math.nextafter()}$ : return the next floating-point value after x towards y . (Contributed by Victor Stinner in bpo-39288.) 

Added math.ulp() : return the value of the least significant bit of a float. (Contributed by Victor Stinner in bpo-39310.) 

## 6.19 multiprocessing 

The multiprocessing.SimpleQueue class has a new close() method to explicitly close the queue. (Con- tributed by Victor Stinner in bpo-30966.) 

## 6.20 nntplib 

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.) 

## 6.21 os 

Added$_{CLD_KILLED}$ and$_{CLD_STOPPED}$ for$_{si_code}$. (Contributed by Dong-hee Na in bpo-38493.) 

Exposed the Linux-specific$_{os.pidfd_open()}$ (bpo-38692) and$_{os.P_PIDFD}$ (bpo-38713) for process man- agement with file descriptors. 

The$_{os.unsetenv()}$ function is now also available on Windows. (Contributed by Victor Stinner in bpo-39413.) 

The$_{os.putenv()}$ and$_{os.unsetenv()}$ functions are now always available. (Contributed by Victor Stinner in bpo-39395.) 

Added$_{os.waitstatus_to_exitcode()}$ function: convert a wait status to an exit code. (Contributed by Victor Stinner in bpo-40094.) 

## 6.22 pathlib 

Added$_{pathlib.Path.readlink()}$ which acts similarly to$_{os.readlink()}$ . (Contributed by Girts Folk- manis in bpo-30618) 

## 6.23 pdb 

On Windows now$_{Pdb}$ supports$_{~/.pdbrc}$ . (Contributed by Tim Hopper and Dan Lidral-Porter in bpo-20523.) 

