'Get pid files for this server
:param: number, if supplied will only lookup the nth server
:returns: list of pid files'

def pid_files(self, **kwargs):

    if (self.conf is not None):
        pid_files = search_tree(self.run_dir, ('%s*' % self.server), exts=[(self.conf + '.pid'), (self.conf + '.pid.d')])
    else:
        pid_files = search_tree(self.run_dir, ('%s*' % self.server))
    if kwargs.get('number', 0):
        conf_files = self.conf_files(**kwargs)
        pid_files = [pid_file for pid_file in pid_files if (self.get_conf_file_name(pid_file) in conf_files)]
    return pid_files
