function _getSuperClassInfo(node, state) {
  var ret = {
    name: null,
    expression: null
  };
  if (node.superClass) {
    if (node.superClass.type === Syntax.Identifier) {
      ret.name = node.superClass.name;
    } else {
      // Extension from an expression
      ret.name = _generateAnonymousClassName(state);
      ret.expression = state.g.source.substring(
        node.superClass.range[0],
        node.superClass.range[1]
      );
    }
  }
  return ret;
}
Extracts super class information from a class node.

Information includes name of the super class and/or the expression string
(if extending from an expression)

@param {object} node
@param {object} state
@return {object}