i want to make a cli command that ...

[nilamo]

import sys


def get_buffer_size():
    buffer_size = 1
    if len(sys.argv) > 1:
        buffer_size = abs(int(sys.argv[1]))
    return buffer_size


def consume_input(buffer_size):
    buffer = []
    head_sent = False
    for line in sys.stdin:
        buffer.append(line)
        if len(buffer) > buffer_size:
            if not head_sent:
                head_sent = True
                for line in buffer:
                    print(line, end="")
                buffer = []
            else:
                buffer.pop(0)

    if head_sent and buffer:
        print("-" * 78)
    for line in buffer:
        print(line, end="")


if __name__ == "__main__":
    try:
        buffer_size = get_buffer_size()
        consume_input(buffer_size)
    except ValueError as err:
        print("Invalid buffer size.  Any argument to this script should be a number.")

Output:
E:\Projects\etc>pip help | headtail.py

Usage:
------------------------------------------------------------------------------
                              download. Implied with --no-index.

E:\Projects\etc>pip help | headtail.py -4

Usage:
  pip <command> [options]

Commands:
------------------------------------------------------------------------------
  --disable-pip-version-check
                              Don't periodically check PyPI to determine
                              whether a new version of pip is available for
                              download. Implied with --no-index.