code: def upgrade():
      bind = op.get_bind()
  
      # Uniqueness constraint if present only exists in MySQL.
      if isinstance(bind.dialect, MySQLDialect):
          constraint_name = generic_find_uq_constraint_name(
              "tables", {"table_name"}, Inspector.from_engine(bind)
          )
  
          if constraint_name:
              op.drop_constraint(
                  constraint_name, "tables", type_="unique"
              )
  
imports: from alembic import op
  from sqlalchemy.dialects.mysql.base import MySQLDialect
  from sqlalchemy.engine.reflection import Inspector
  from superset.utils.core import generic_find_uq_constraint_name
label_desc: Use image node_id 1 for calling a global function with example usage: upgrade() without return types