{
  global:
    extern "C++" {
      *protobuf::*;
      *substrait::*;
    };

  local:
    extern "C++" {
      # Hide symbols of glog, gflags (protobuf is made global at above).
      *google::*;
      fL*::FLAGS_*;
      gflags_mutex_namespace::*;
      glog_internal_namespace_::*;
    };
};