new_contents: from alembic import op
  
  revision = '30_rm_unique_constraint'
  down_revision = '20_initialise_data'
  
  
  def upgrade():
      op.drop_constraint("users_name_key", "users")
  
  
  def downgrade():
      op.create_unique_constraint("users_name_key", "users", ["name"])
subject: Remove unique constraint on users.name