code: function addToFooter(schema, path, unwind) {
      Object.keys(schema).forEach(function(name) {
        if (name.slice(0,2) == '__')
          return true;
        if (!path && (name == 'id' || name == '_id'))
          return;
        if (model.schema.nested[path+name]) {
          addToFooter(schema[name], path+name+'.', '')
        } else if (schema[name] && schema[name].tree) {
          addToFooter(schema[name].tree, path+name+'.');
          if (typeof schema[name].options.strict === 'boolean' && !schema[name].options.strict) {
            footer.push({name:name, path: path+name+'.*'});
          }
        } else if (name === unwind) {
          addToFooter(schema[name][0].tree, path+name+'.0.')
          if (typeof schema[name][0].options.strict === 'boolean' && !schema[name][0].options.strict) {
            footer.push({name:name, path: path+name+'.0.*'});
          }
        } else {
          if (skipField(path+name)) {
            return;
          }
          footer.push({name:name, path: path+name})
        }
      });
    }
docs: only include leaves