Sharepoint -Check SPGroup

public bool isGroupExist(string groupName)
{
SPSite _objSite;
SPWeb _objWeb;
bool flag = true;
string _siteUrl = SPContext.Current.Site.Url;
SPSecurity.RunWithElevatedPrivileges(delegate()
{
using (_objSite = new SPSite(_siteUrl))
{
using (_objWeb = _objSite.OpenWeb())
{
if (_objWeb.SiteGroups.Cast().Any(g => string.Compare(g.Name, groupName, true) == 0))
{
flag = false;

}
}
}
}); return flag;
}