_getType (value) {
    if (value instanceof Array) {
      return 'array'
    }
    if (value instanceof Object) {
      return 'object'
    }
    if (typeof (value) === 'string' && typeof (parseString(value)) !== 'string') {
      return 'string'
    }

    return 'auto'
  }
get the type of a value
@param {*} value
@return {String} type   Can be 'object', 'array', 'string', 'auto'
@private