(optional) Pass options to the constructor. Valid options are :
xhtml (sets xhtml compliance),
tab (sets indent string),
filename (name of file to be parsed),
cache (determines whether the nocache headers are sent),
oneline (whether to output each definition on one line),
groupsfirst (determines whether to output groups before elements)
allowduplicates (allow to have duplicate rules in selector)
(optional) has to configure error handler