Shuffling a list while keeping order relative to related elements

I'm looking to shuffle a list of the elements a1, ... a6, ... e1, ..., e6

while keeping two rules:

if I loop though the list and filter out a specific letter or number it should be in order:

a1, a2, a3... or a1, b1, c1 ...

How can I shuffle the list keeping these rules? Is there a python library. for such a task?

Here's an example of a shuffle that would fit the criteria:

a1, b1, a2, b2, c1, a3, d1, c2, d2, e1, a4, b3, c3, d3, b4, d4, c4, a5, e2, d5, e3, c5, a6, b5, e4, a7, b6, c6, b7, d6, e5, e6, c7, d7, e7