How to make it so the close button on the ttk notebook tab is specific and does not appear for all tabs

Question

I have a tkinter.ttk.notebook in my program that has close buttons for all tabs that are created in it.

But I want that the first tab created shall not bear a close button acting like a welcome tab that cannot be closed by the user.

I have a ttk notebook wherein I have a welcome tab which I always want to be there and not have the close buttons, but I also want the other tabs to have the close button. Also The close buttons I am talking about is from this post.

So if there is a way to make the close buttons specific for only some tabs and not all, then it might help. Unfortunately the post from where I picked up the logic/code for the close buttons does not mention any way to have close buttons for some tabs and not for the others.

My code -:

try:
    import Tkinter as tk
    import ttk
except ImportError:  # Python 3
    import tkinter as tk
    from tkinter import ttk

class CustomNotebook(ttk.Notebook):
    """A ttk Notebook with close buttons on each tab"""

    __initialized = False

    def __init__(self, *args, **kwargs):
        if not self.__initialized:
            self.__initialize_custom_style()
            self.__inititialized = True

        kwargs["style"] = "CustomNotebook"
        ttk.Notebook.__init__(self, *args, **kwargs)

        self._active = None

        self.bind("<ButtonPress-1>", self.on_close_press, True)
        self.bind("<ButtonRelease-1>", self.on_close_release)

    def on_close_press(self, event):
        """Called when the button is pressed over the close button"""

        element = self.identify(event.x, event.y)

        if "close" in element:
            index = self.index("@%d,%d" % (event.x, event.y))
            self.state(['pressed'])
            self._active = index
            return "break"

    def on_close_release(self, event):
        """Called when the button is released"""
        if not self.instate(['pressed']):
            return

        element =  self.identify(event.x, event.y)
        if "close" not in element:
            # user moved the mouse off of the close button
            return

        index = self.index("@%d,%d" % (event.x, event.y))

        if self._active == index:
            self.forget(index)
            self.event_generate("<<NotebookTabClosed>>")

        self.state(["!pressed"])
        self._active = None

    def __initialize_custom_style(self):
        style = ttk.Style()
        self.images = (
            tk.PhotoImage("img_close", data='''
                R0lGODlhCAAIAMIBAAAAADs7O4+Pj9nZ2Ts7Ozs7Ozs7Ozs7OyH+EUNyZWF0ZWQg
                d2l0aCBHSU1QACH5BAEKAAQALAAAAAAIAAgAAAMVGDBEA0qNJyGw7AmxmuaZhWEU
                5kEJADs=
                '''),
            tk.PhotoImage("img_closeactive", data='''
                R0lGODlhCAAIAMIEAAAAAP/SAP/bNNnZ2cbGxsbGxsbGxsbGxiH5BAEKAAQALAAA
                AAAIAAgAAAMVGDBEA0qNJyGw7AmxmuaZhWEU5kEJADs=
                '''),
            tk.PhotoImage("img_closepressed", data='''
                R0lGODlhCAAIAMIEAAAAAOUqKv9mZtnZ2Ts7Ozs7Ozs7Ozs7OyH+EUNyZWF0ZWQg
                d2l0aCBHSU1QACH5BAEKAAQALAAAAAAIAAgAAAMVGDBEA0qNJyGw7AmxmuaZhWEU
                5kEJADs=
            ''')
        )

        style.element_create("close", "image", "img_close",
                            ("active", "pressed", "!disabled", "img_closepressed"),
                            ("active", "!disabled", "img_closeactive"), border=8, sticky='')
        style.layout("CustomNotebook", [("CustomNotebook.client", {"sticky": "nswe"})])
        style.layout("CustomNotebook.Tab", [
            ("CustomNotebook.tab", {
                "sticky": "nswe",
                "children": [
                    ("CustomNotebook.padding", {
                        "side": "top",
                        "sticky": "nswe",
                        "children": [
                            ("CustomNotebook.focus", {
                                "side": "top",
                                "sticky": "nswe",
                                "children": [
                                    ("CustomNotebook.label", {"side": "left", "sticky": ''}),
                                    ("CustomNotebook.close", {"side": "left", "sticky": ''}),
                                ]
                        })
                    ]
                })
            ]
        })
    ])

if __name__ == "__main__":
    root = tk.Tk()

    notebook = CustomNotebook(width=200, height=200)
    notebook.pack(side="top", fill="both", expand=True)
    
    welcome_frame = tk.Frame(notebook)
    # I want this tab to have no close button
    notebook.add(welcome_frame, text = 'Welcome')
    
    for color in ("red", "orange", "green", "blue", "violet"):
        frame = tk.Frame(notebook, background=color)
        notebook.add(frame, text=color)

    root.mainloop()