question: public JSONBuffer appendKeyHash ( Object key ) { if ( stack . empty ( ) || stack . peek ( ) != Operand . HASH ) { throw new JSONException ( "Appending key-value outside of hash context." ) ; } addQuotedString ( key ) ; buffer . append ( ":" ) ; buffer . append ( "{" ) ; stack . push ( Operand . HASH ) ; return this ; }
target:  Append a key an start a new hash