Alembic migrate enum

revision.py

from alembic import op
from sqlalchemy.dialects.postgresql import ENUM
from sqlalchemy import Column

def upgrade():
    enum = ENUM("one", "two", "three", name="pgenum", create_type=False)
    enum.create(op.get_bind(), checkfirst=False)
    op.create_table("sometable", 
        Column("data", enum)
    )

def downgrade():
    op.drop_table("sometable")
    ENUM(name="pgenum").drop(op.get_bind(), checkfirst=False)