CHECK_MUTABLE     309 src/string.c       CHECK_MUTABLE(x);
CHECK_MUTABLE     328 src/string.c       CHECK_MUTABLE(x);
CHECK_MUTABLE     754 src/string.c       CHECK_MUTABLE(x);
CHECK_MUTABLE     766 src/string.c       CHECK_MUTABLE(x);
CHECK_MUTABLE     784 src/string.c       CHECK_MUTABLE(x);
CHECK_MUTABLE    1088 src/string.c       CHECK_MUTABLE(str);