Currently it is quite inconvenient to add a single piece of information deep in the metainfo hierarchy, especially if this involves repeating sections. E.g. if I want to update the band gap value in a normalizer: ```python if not archive.results: archive.results = Results() if not archive.results.properties: archive.results.properties = Properties() if not archive.results.properties.electronic: archive.results.properties.electronic = ElectronicProperties() if not archive.results.properties.electronic.band_structure: archive.results.properties.optoelectronic.band_structure.append(BandStructure()) if not archive.results.properties.electronic.band_structure[0].band_gap: not archive.results.properties.electronic.band_structure[0].band_gap.append(BandGap()) archive.results.properties.electronic.band_structure[0].band_gap[0].value = 5 * ureg.eV ``` I would propose simplifying such tasks by creating a new function for sections called `m_setdefault` (in accordance with the python dict [setdefault](https://docs.python.org/3.9/library/stdtypes.html?highlight=setdefault#dict.setdefault) method) which would help with this. The operation above would be achieved with: ```python band_gap = archive.m_setdefault('results.properties.electronic.band_structure.band_gap') band_gap.value = 5 * ureg.eV ``` This function create any missing sections along the path and will raise an exception if the path cannot be unambiguously resolved (e.g. there are already several repeating sections).