accessing the content of the interface "isaac_ros_tensor_list_interfaces/msg/TensorList"

[NirshalChandraSekar]

I am subscribing to this topic /tensor_sub of message type "isaac_ros_tensor_list_interfaces/msg/TensorList".
The message is structure this way:
std_msgs/Header header
builtin_interfaces/Time stamp
int32 sec
uint32 nanosec
string frame_id

A list of tensors
Tensor[] tensors
string name
TensorShape shape
uint8 rank
uint32[] dims
int32 data_type
uint64[] strides
uint8[] data
How do i access the frame_id in the header of this message. I tried doing "msg.header.frame_id" but its not working