print_numbered_list.py

from math import log10
from typing import Sequence

def print_numbered_list(items: Sequence, fmt='{num}. {item}') -> None:
    """Display as a numbered list where the items are left aligned.

    items:
        A list of printable items.

    fmt:
        The output format where `num` will be right aligned and
        `item` will be left aligned.

        Note: Don't include alignments in the `fmt` string; they're
        already done inside the function before it uses the format.

    >>> items = [
    ...    'Cerium', 'Lanthanum', 'Neodynium', 'Yttirium', 'Praesodynium',
    ...    'Samarium', 'Gadolinium', 'Dysprosium', 'Erbium', 'Ytterbium'
    ... ]
    >>> print_numbered_list(items)
     1. Cerium
     2. Lanthanum
     3. Neodynium
     4. Yttirium
     5. Praesodynium
     6. Samarium
     7. Gadolinium
     8. Dysprosium
     9. Erbium
    10. Ytterbium

    >>> items = items[:2]
    >>> print_numbered_list(items)
    1. Cerium
    2. Lanthanum

    >>> print_numbered_list(items, fmt='{num} ... {item}')
    1 ... Cerium
    2 ... Lanthanum

    """
    num_width = int(log10(len(items))) + 1
    for num, item in enumerate(items, 1):
        num =str(num).rjust(num_width)
        print(fmt.format(num=num, item=item))