On Stack­Over­flow, someone wanted to print triangles in Python in an M-shape. Various clumsy solutions were offered.

Here’s mine which uses the left- and right-jus­ti­fi­ca­tion features of str.format.

• "{0}+++{0}".format('Hello!') produces two copies of the zeroth argument to format (here 'Hello!'), separated by three plusses: Hello!+++Hello!.
• "{:<4}".format('x') left-justifies 'x' in a 4-character field; i.e., 'x   '.
• "{:>4}".format('x') right-justifies 'x' in a 4-character field; i.e., '   x'.
• "{:>{}}".format('x', width) right-justifies 'x' in a width-character field.
• 'ab' * 4 yields 4 copies of 'ab'; i.e., 'abababab'.

Putting them together:

.. code:: pycon

>>> WIDTH = 4
>>>
>>> for a in range(1, WIDTH+1):
...     print("{0:<{1}}{0:>{1}}".format('*' * a, WIDTH))
...
*      *
**    **
***  ***
********

Handy references: PyFormat and Python String Format Cookbook.