code: function (props, propName, componentName) {
      // Only accept a single child, of the appropriate type
      //credits: http://www.mattzabriskie.com/blog/react-validating-children
      let prop = props[propName];
      let types = ['svg'];
      if (React.Children.count(prop) !== 1 ||
        types.indexOf(prop.type) === -1) {
        return new Error(
          '`' + componentName + '` ' +
          'should have a single child of the following types: ' +
          ' `' + types.join('`, `') + '`.'
        );
      }
      if (!prop.props.hasOwnProperty('width') || !prop.props.hasOwnProperty('height')) {
        return new Error('SVG should have props `width` and `height`');
      }
  
    }
docs: *********************************************************************** /* Children Check *********************************************************************** accept only one node SVG