Python reading a complicated .txt file
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I have a .txt with data like this:

    >ENSMUSG00000002477|ENSMUST00000002551|*some junk information*...etc.|
    TCGCGCGTCCGCAGGCCTCCGCGCGCTTTTCCG....etc.
    >ENSMUSG00000002835|ENSMUST00000002914|...etc.|
    GCAGAAGTGACACCGGTGGGAGGCG...etc.

I have codes written to get me to a point I have the names ENSMUSG0000000xxxx

I want to pick out the names I have from the .txt with the next line e.g."TACGTACG" read in a triple form e.g."TAC" "GTA"

And then I want to do the same thing but instead of reading from the 1st letter I want to start at the 2nd, using the above example it will read "ACG" and "TAG"

and the same thing again but skip the first 2 letters

I really don't know how would I do it especially the reading 3 letters part. Can someone give me a hand please?
