I'm new to GAP, and I tried to adjust the code that ahulpke wrote at the link: Faithful permutation representation
to construct a faithful representation of the group $C_2\times (C_4\rtimes C_4)$ using "three orbits". I adujested the code by adding a subgroup $H_3$, and
cos:=Concatenation(RightCosets(G,H1),RightCosets(G,H2),RightCosets(G,H3));
But it didn’t work with me and I believe I made an error.
Do any GAP's codes exist that will give me a faithful permutation representation of a group with respect to provided three subgroups, where the intersection of both subgroups has a trivial core?
I appreciate your help, thank you!