code: def value(self):
      return self._value
  
file_path: evadb/evadb/expression/constant_value_expression.py
imports: from typing import Any
  import numpy
  import pandas
  from evadb.catalog.catalog_type import ColumnType
  from evadb.expression.abstract_expression import AbstractExpression, ExpressionType
  from evadb.models.storage.batch import Batch
label_desc: Use image node_id 4 for calling the ConstantValueExpression obj's underlying member method code with example usage: obj.value() and returns: self