Set process name in python

How to set process name from inside it? I know that nmap can fake name, but the question is how to do this from python.
The code that is doing this magic in nmap:

# from nmap.cc
  if (quashargv) {
    size_t fakeargvlen = strlen(FAKE_ARGV), argvlen = strlen(argv[0]);
    if (argvlen < fakeargvlen)
      fatal("If you want me to fake your argv, you need to call the program with a longer name.  Try the full pathname, or rename it fyodorssuperdedouperportscanner");
    strncpy(argv[0], FAKE_ARGV, fakeargvlen);
    memset(&argv[0][fakeargvlen], '\0', strlen(&argv[0][fakeargvlen]));
    for(i=1; i < argc; i++)
      memset(argv[i], '\0', strlen(argv[i]));
  }

There are some possible ways of doing this from python. Some guys suggest using prctl ioctl. But it didn't worked for me. Also the module proctitle haven't done what I expected.
From time I found rtgraph3d project, I'm a fan of PyInline module. Here's my python code that's working (for me):

import PyInline, time

m = PyInline.build(code=r"""
    #include <Python.h>
    #include <stdio.h>
    #include <string.h>
    
    void set_argv(char *str){
        int argc;
        char **argv;
        Py_GetArgcArgv(&argc, &argv);
        strncpy(argv[0], str , strlen(str));
        memset(&argv[0][strlen(str)], '\0', strlen(&argv[0][strlen(str)]));
    }
    """, language="C")

m.set_argv('very custom python process name')
time.sleep(100)

It looks funny from ps:

majek@tigger:~$ ps aux|grep very
majek    11688  2.6  0.4   7192  4360 pts/21   S+   00:20   0:00 very custom python process name