py匹配字符串中间的字符串

python 正则表达式，怎样匹配以某个字符串开头，以某个字符串结尾的情况？

str ="abcdefg123213qwe"

正则表达式:^abc(.*?)qwe$

dbconfig = open("./config.xml", "r")
configStr = dbconfig.read();


pattern = re.compile("<HostName>(.*?)</HostName>")
HostName = re.findall(pattern, configStr)[0]