def load_phases(self, filename, insert_index=None):
"""
Loads all :class:`~pyxrd.phase.models.Phase` objects from the file
'filename'. An optional index can be given where the phases need to be
inserted at.
"""
insert_index = not_none(insert_index, 0)
for phase in Phase.load_phases(filename, parent=self):
self.phases.insert(insert_index, phase)
insert_index += 1
