function run() {

  this.substVarRefs = this.substituteVariableReferences;

  const fn = command[arguments[0]];
  let result = null;

  if (typeof fn === 'function') {
    const args = Array.prototype.slice.call(arguments,1);
    result = fn.apply(this, args);
  }

  return (typeof result === 'string' ? result : '');

}
@this MacroCallWidget
@return {string} the result of the operation or an empty string.
@private