code: function LowlevelUp(backend, location, options) {
    if (!(this instanceof LowlevelUp))
      return new LowlevelUp(backend, location, options);
  
    assert(typeof backend === 'function', 'Backend is required.');
    assert(typeof location === 'string', 'Filename is required.');
  
    this.options = new LLUOptions(options);
    this.backend = backend;
    this.location = location;
    this.locker = new Lock();
  
    this.loading = false;
    this.closing = false;
    this.loaded = false;
  
    this.db = null;
    this.binding = null;
  
    this.init();
  }
docs: Extremely low-level version of levelup.
  
  This avoids pulling in extra deps and
  lowers memory usage.
  
  @alias module:db.LowlevelUp
  @constructor
  @param {Function} backend - Database backend.
  @param {String} location - File location.
  @param {Object?} options - Leveldown options.