[Python] How can I append two arrays, but have the second array in wide format?

If I have two arrays in python:

Array 1 =

[[1 2]
[3 4]]

Array 2 =
[[5 6]]


How can I use .append or .extend to create an array, such that:

Array 3:
[[1 2 5 6]
[3 4 5 6]]

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