NameError: name 'BramProcessor' is not defined

When following the “Testing the Tutorial Overlay under 4-Packaging-An-Overlay” below issue occurred on pynq-z2:

NameError Traceback (most recent call last)
in ()
2 sys.path.insert(0, ‘/home/xilinx/RISC-V-On-PYNQ/riscvonpynq/picorv32/’)
3
----> 4 from tut.tutorial import TutorialOverlay
5
6 overlay = TutorialOverlay(“tutorial.bit”)

/home/xilinx/RISC-V-On-PYNQ/riscvonpynq/picorv32/tut/init.py in ()
----> 1 from . import tutorial
2 from . import build

/home/xilinx/RISC-V-On-PYNQ/riscvonpynq/picorv32/tut/tutorial.py in ()
17 pass
18
—> 19 class TutorialProcessor(BramProcessor):
20 “”"Hierarchy driver for the PicoRV32 BRAM Processor
21

NameError: name ‘BramProcessor’ is not defined

Can anyone help me know what went wrong.

facing this issue…