Not able to get the total volume of the model using PythonOCC

Question

I am trying to print the total volume of my model in the terminal, but it is not showing anything. I referred to "https://stackoverflow.com/questions/66929762/extract-volume-from-a-step-file" but was not helpul. Below is my code

from OCC.Display.SimpleGui import init_display
from OCC.Core.STEPControl import STEPControl_Reader
from OCC.Extend.DataExchange import read_step_file
from OCC.Core.GProp import GProp_GProps
from OCC.Core.BRepGProp import brepgprop_VolumeProperties

def open_step_file():
    # Open a file dialog to select the STEP file
    file_path = filedialog.askopenfilename(
        title="Geometry Construction",
        filetypes=[("STEP Files", "*.stp")]
    )
    if file_path:
        # Initialize the display
        display, start_display, _, _ = init_display()

        # Read the STEP file
        step_reader = STEPControl_Reader()
        step_reader.ReadFile(file_path)

        # Transfer the contents of the STEP file to the display
        step_reader.TransferRoots()
        shape = step_reader.Shape()
        display.DisplayShape(shape, update=True)

        # Start the display
        start_display()

def calculate_total_volume(file_path):
    if file_path:
        total_volume = 0.0
        for shape in file_path:
            volume_props = GProp_GProps()
            brepgprop_VolumeProperties(shape, volume_props)
            total_volume += volume_props.Mass()
            print(total_volume)

Can anyone please help me on this?