SCM_CLASS_PORT_ERROR  613 src/error.c                peclass = SCM_CLASS_PORT_ERROR; break;
SCM_CLASS_PORT_ERROR  923 src/error.c        Scm_InitStaticClassWithMeta(SCM_CLASS_PORT_ERROR,
SCM_CLASS_PORT_ERROR  161 src/gauche/exception.h #define SCM_PORT_ERROR_P(obj)    SCM_ISA(obj, SCM_CLASS_PORT_ERROR)