Call other processes.
        args - list of command args
        devnull - whether to pipe stdout to /dev/null (or equivalent)

def call(self, args, devnull=False):
        """Call other processes.
        args - list of command args
        devnull - whether to pipe stdout to /dev/null (or equivalent)
        """
        if self.debug:
            click.echo(subprocess.list2cmdline(args))
            click.confirm('Continue?', default=True, abort=True)
        try:
            kwargs = {}
            if devnull:
                # Pipe to /dev/null (or equivalent).
                kwargs['stderr'] = subprocess.STDOUT
                kwargs['stdout'] = self.FNULL
            ret_code = subprocess.call(args, **kwargs)
        except subprocess.CalledProcessError:
            return False
        return ret_code