param from param to export function * charRange ( from , to ) { let i = typeof from === "string" ? from . charCodeAt ( 0 ) : from ; const end = typeof to === "string" ? to . charCodeAt ( 0 ) : to ; if ( i <= end ) { for ( ; i <= end ; i ++ ) { yield String . fromCharCode ( i ) ; } } else { for ( ; i >= end ; i -- ) { yield String . fromCharCode ( i ) ; } } }