function pkg2alias( pkg ) {
	if ( !isString( pkg ) ) {
		throw new TypeError( format( 'invalid argument. Must provide a string. Value: `%s`.', pkg ) );
	}
	if ( hasOwnProp( PKG_TO_ALIAS, pkg ) ) {
		return PKG_TO_ALIAS[ pkg ];
	}
	pkg = standalone2pkg( pkg );
	if ( hasOwnProp( PKG_TO_ALIAS, pkg ) ) {
		return PKG_TO_ALIAS[ pkg ];
	}
	return null;
}
Returns the alias associated with a specified package name.

@param {string} pkg - package name
@throws {TypeError} must provide a string
@returns {(string|null)} alias

@example
var v = pkg2alias( '@stdlib/math/base/special/sin' );
// returns 'base.sin'