class_docstr: This dataclass stores metadata to perform apply and merge operation.
  
  Arguments:
      func_expr(FunctionExpression): parameterized function expression that
          reference columns from a table expression that precedes it.
      do_unnest(bool): if True perform unnest operation on the output of FunctionScan
code: def alias(self):
      return self._alias
  
file_path: evadb/evadb/plan_nodes/apply_and_merge_plan.py
imports: from evadb.expression.function_expression import FunctionExpression
  from evadb.parser.alias import Alias
  from evadb.plan_nodes.abstract_plan import AbstractPlan
  from evadb.plan_nodes.types import PlanOprType
label_desc: Use image node_id 3 for calling the ApplyAndMergePlan obj's underlying member method code with example usage: obj.alias() and returns: self