question: void checkFrameValue ( final Object value ) { if ( value == Opcodes . TOP || value == Opcodes . INTEGER || value == Opcodes . FLOAT || value == Opcodes . LONG || value == Opcodes . DOUBLE || value == Opcodes . NULL || value == Opcodes . UNINITIALIZED_THIS ) { return ; } if ( value instanceof String ) { checkInternalName ( ( String ) value , "Invalid stack frame value" ) ; return ; } if ( ! ( value instanceof Label ) ) { throw new IllegalArgumentException ( "Invalid stack frame value: " + value ) ; } else { usedLabels . add ( ( Label ) value ) ; } }
target:  Checks a stack frame value.