plot_pie_sum appends the builtin slice type instead of the computed slice size

[ivankrylov]

src/graphing/plotting.py:110-113:
for idx, datapoints in enumerate(datapoint_groups):
pslice = sum(datapoints)
pie_slices_sizes.append(slice) # <-- appends builtin slice, not pslice
labels[idx] = labels[idx] + " : " + str(pslice)
pslice is computed and used in the label, but the list gets the builtin slice type
object. So plot.pie() receives a list of type objects rather than numbers.