Here is an sample of CSV input:

"time","forces"
0,0
0.5,0.9

when calling has_header() from csv.py on this sample, it returns false.
Why? because 0 and 0.5 don't belong to the same type and thus the column is discarded by the heuristic.

I think the heuristic will better work if rather than just comparing number types, it would also consider casting the values in this order int -> float -> complex. If the values are similar then consider this upgraded type as the type of the column.

In the end, this file would be considered float columns with headers.