Inconsistent preset API

[kjappelbaum]

chem-caption/src/chemcaption/featurize/composition.py

Line 424 in 5d09859

def __init__(self, preset: Optional[List[str]] = None):

[kjappelbaum]

i think the presets should be handled by a classmethod and the __init__ should take the raw input (list of elements in this case)