Return a dict containing user-specified plotting options.

def _init_kws(self, **kws_usr):
        """Return a dict containing user-specified plotting options."""
        kws_self = {}
        user_keys = set(kws_usr)
        for objname, expset in self.exp_keys.items():
            usrkeys_curr = user_keys.intersection(expset)
            kws_self[objname] = get_kwargs(kws_usr, usrkeys_curr, usrkeys_curr)
        dpi = str(kws_self['dag'].get('dpi', self.dflts['dpi']))
        kws_self['dag']['dpi'] = dpi
        return kws_self