rb_f_exec         641 include/ruby/intern.h NORETURN(VALUE rb_f_exec(int, const VALUE*));
rb_f_exec        7575 process.c          rb_define_global_function("exec", rb_f_exec, -1);
rb_f_exec        7601 process.c          rb_define_singleton_method(rb_mProcess, "exec", rb_f_exec, -1);