docs: function parseloopspec(p){
      var m = p.match( /^(\w+)\s*<-\s*(\S+)?$/ );
      if(m === null){
        error('bad loop spec: "' + p + '"');
      }
      if(m[1] === 'item'){
        error('"item<-..." is a reserved word for the current running iteration.\n\nPlease choose another name for your loop.');
      }
      if( !m[2] || (m[2] && (/context/i).test(m[2]))){ //undefined or space(IE)
        m[2] = function(ctxt){return ctxt.context;};
      }
      return {name: m[1], sel: m[2]};
    }