docs: function Parser(tokens, options) {
    options = options || {};
    if (!Array.isArray(tokens)) {
      throw new Error('Expected tokens to be an Array but got "' + (typeof tokens) + '"');
    }
    if (typeof options !== 'object') {
      throw new Error('Expected "options" to be an object but got "' + (typeof options) + '"');
    }
    this.tokens = new TokenStream(tokens);
    this.filename = options.filename;
    this.src = options.src;
    this.inMixin = 0;
    this.plugins = options.plugins || [];
  }