Missing entries in MadArray.__str__ for complex entries

Method MadArray.__str__ replace missing entries by x+0.j when data is complex, whatever complex_masking is. It may be appropriate to obtain x+x.j when complex_masking is False and to display available magnitude or angle when complex_masking is True (e.g., by displaying one array with all the information or by display one magnitude array and one angle array). What do you think is doable/appropriate? See cell 6 in tutorial mad_array.ipynb.