Create a list of 2 variables

Question

If I have variables x and y, such that:

• x is always a string
• y can either be a string or a list of strings

How can I create a list z == [x, <all elements of y>]?

For instance:

x = 'x'
y = 'y'
# create z
assert z == ['x', 'y']

x = 'x'
y = ['y', 'y2']
# create z
assert z == ['x', 'y', 'y2']

Answer 1

z = [x] + (y if isinstance(y, list) else [y])

Generally I'd avoid having a y that could be either a string or a list, though: it seems unnecessary.