old_contents: // Simple, internal Object.assign() polyfill for options objects etc.
  
  module.exports = Object.assign != null ? Object.assign.bind( Object ) : function( tgt, ...srcs ){
    srcs.forEach( src => {
      Object.keys( src ).forEach( k => tgt[k] = src[k] );
    } );
  
    return tgt;
  };
  
new_contents: // Simple, internal Object.assign() polyfill for options objects etc.
  
  module.exports = Object.assign != null ? Object.assign.bind( Object ) : function( tgt, ...srcs ){
    srcs.filter(src => src != null).forEach( src => {
      Object.keys( src ).forEach( k => tgt[k] = src[k] );
    } );
  
    return tgt;
  };
  
subject: Make internal assign polyfill more compatible on really old browsers like IE9