bug476.m:059: In instance declaration for `input_stream(jinput_stream)':
bug476.m:059:   error: the type class has no predicate method named `mark'/4.
bug476.m:068: Error: the predicate `bug476.mark'/4 is multiply defined.
bug476.m:034:   Here is its previous definition.
bug476.m:070: Error: clause for predicate `input_stream_mark'/3 without a
bug476.m:070:   corresponding `:- pred' declaration.