Creating a mutable ARRAY data type in sqlalchemy

something.py

class Something(Base):
    __tablename__ = 'yaddayadda'

    id = Column(Integer, primary_key=True)
    data = Column(MutableList.as_mutable(ARRAY(String(100))))

sqlal_mutable_array.py

from sqlalchemy.ext.mutable import Mutable
from sqlalchemy.dialects.postgresql import ARRAY

class MutableList(Mutable, list):
    def append(self, value):
        list.append(self, value)
        self.changed()

    @classmethod
    def coerce(cls, key, value):
        if not isinstance(value, MutableList):
            if isinstance(value, list):
                return MutableList(value)
            return Mutable.coerce(key, value)
        else:
            return value