code: function Icns( filename, options ) {
  
    if( !(this instanceof Icns) ) {
      return new Icns( filename, options )
    }
  
    if (filename instanceof Buffer) {
      this.filename = 'buffer'
      this._buffer = filename
    } else {
      this.filename = filename
      this._buffer = null;
    }
  
    this.fd = null
    this.options = Object.assign({}, Icns.defaults, options)
    this.header = new Icns.Header()
    this.entries = []
  }
docs: Icns
  @constructor
  @returns {Icns}