code: function getBinaryDir() {
    var binaryDir;
  
    if (getArgument('--sass-binary-dir')) {
      binaryDir = getArgument('--sass-binary-dir');
    } else if (process.env.SASS_BINARY_DIR) {
      binaryDir = process.env.SASS_BINARY_DIR;
    } else if (process.env.npm_config_sass_binary_dir) {
      binaryDir = process.env.npm_config_sass_binary_dir;
    } else if (pkg.nodeSassConfig && pkg.nodeSassConfig.binaryDir) {
      binaryDir = pkg.nodeSassConfig.binaryDir;
    } else {
      binaryDir = defaultBinaryDir;
    }
  
    return binaryDir;
  }
docs: Get binary dir.
  If environment variable SASS_BINARY_DIR,
  .npmrc variable sass_binary_dir or
  process argument --sass-binary-dir is provided,
  select it by appending binary name, otherwise
  use default binary dir.
  Once the primary selection is made, check if
  callers wants to throw if file not exists before
  returning.
  
  @api public