class_docstr: The plan first evaluates the `search_query_expr` expression and searches the output
  in the vector index. The plan finally projects `limit_count` number of results.
  
  Arguments:
      index_name (str): The vector index name.
      limit_count (ConstantValueExpression): Number of top results to project.
      search_query_expr (FunctionExpression): function expression to evaluate, whose
      results will be searched in the vector index.
class_docstr_tok: ["The","plan","first","evaluates","the","`","search_query_expr","`","expression","and","searches","the","output","in","the","vector","index",".","The","plan","finally","projects","`","limit_count","`","number","of","results",".","Arguments",":","index_name","(","str",")",":","The","vector","index","name",".","limit_count","(","ConstantValueExpression",")",":","Number","of","top","results","to","project",".","search_query_expr","(","FunctionExpression",")",":","function","expression","to","evaluate",",","whose","results","will","be","searched","in","the","vector","index","."]
code: def search_query_expr(self):
      return self._search_query_expr
  
file_path: evadb/evadb/plan_nodes/vector_index_scan_plan.py
imports: from evadb.catalog.models.utils import IndexCatalogEntry
  from evadb.expression.constant_value_expression import ConstantValueExpression
  from evadb.expression.function_expression import FunctionExpression
  from evadb.plan_nodes.abstract_plan import AbstractPlan
  from evadb.plan_nodes.types import PlanOprType
label_desc: Use image node_id 4 for calling the VectorIndexScanPlan obj's underlying member method code with example usage: obj.search_query_expr() and returns: self