如何判断python中是否存在进程

#-*- coding:utf-8 -*-
def check_exsit(process_name):
import win32com.client
WMI = win32com.client.GetObject('winmgmts:')
processCodeCov = WMI.ExecQuery('select * from Win32_Process where Name="%s"' % process_name)
if len(processCodeCov) > 0:
    print '%s is exists' % process_name
else:
    print '%s is not exists' % process_name
if __name__ == '__main__':
check_exsit('chrome.exe')