@classmethod<EOL><INDENT>def cascade(cls, ref_cls, field, frames):<DEDENT>
from mongoframes.queries import to_refs<EOL>ids = [to_refs(f[field]) for f in frames if f.get(field)]<EOL>ref_cls.get_collection().delete_many({'<STR_LIT>': {'<STR_LIT>': ids}})<EOL>
Apply a cascading delete (does not emit signals)