code: def call(self, step):
      if step.reduce != "union":
          raise NotSupportedYet(
              f"Only MultipleSteps with type = 'union' is supported. Got '{step.type}'"
          )
      data = None
      for substep in step.steps:
          subdata = self.sql_query.execute_step(substep)
          if data is None:
              data = subdata
          else:
              data.add_records(subdata.get_records())
  
      return data
  
imports: from mindsdb_sql.planner.steps import MultipleSteps
  from mindsdb.api.executor.exceptions import NotSupportedYet
  from .base import BaseStepCall
label_desc: Use image node_id 1 for calling the MultipleStepsCall obj's underlying member method code with example usage: obj.call(step) and returns: data