pysource.py

#!/usr/bin/env python3.9
import argparse
import importlib
import inspect
import pydoc


def get_callable(arg):
    module_str, name = arg.rsplit(".", 1)
    module = importlib.import_module(module_str)
    return getattr(module, name)


def print_source(func, pager=False):
    output = pydoc.pager if pager else print
    output(inspect.getsource(func))


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Read Python source.')
    parser.add_argument("-m", "--module", required=True, dest='module',
                        help='module(.submodule).name')
    parser.add_argument("-p", "--pager", action='store_true', dest='use_pager',
                        help='page output (like Unix more command)')
    args = parser.parse_args()

    func = get_callable(args.module)
    print_source(func, pager=args.use_pager)

This SO answer helped a lot: https://stackoverflow.com/a/8790232

added a pager with pydoc.pager and argparse