I want a script in PyQGIS 3. For example:

This code creates a layout **"2019_A4"** and adds Layout Manager. I need a code to make the same in QGIS 3 using the `QgsLayoutManager` with the `duplicateLayout` method.

Here: https://qgis.org/pyqgis/3.4/core/QgsLayoutManager.html

<!-- language: pyqgis -->

    from qgis.PyQt.QtCore import *
    from qgis.core import *

    # A Project, Manager, & PrintLayout Classes
    project = QgsProject.instance()
    manager = project.layoutManager()

    # layout = QgsPrintLayout(project)
    layout = manager.layoutByName("2019_A4")

    #layout.initializeDefaults()
    #layout.setName('2019_A')
    manager.addLayout(layout)