nl_tokens: A set of objects of the same type
pl_tokens: function ArrayType ( typeSpec ) { if ( typeSpec instanceof Type ) { this . subtype = typeSpec ; } else if ( typeof typeSpec === 'string' ) { this . subtype = types . getType ( typeSpec ) ; if ( this . subtype == null ) { throw new Error ( 'Unknown array subtype: ' + typeSpec ) ; } } else { throw new <mask> ( 'Can\' handle array subtype' ) ; } }