code: def group_by_item(self, tree):
      expr = None
  
      for child in tree.children:
          if isinstance(child, Tree):
              if child.data.endswith("expression"):
                  expr = self.visit(child)
  
      return expr
  
imports: from lark import Token, Tree
  from evadb.expression.tuple_value_expression import TupleValueExpression
  from evadb.parser.select_statement import SelectStatement
  from evadb.parser.table_ref import Alias, JoinNode, TableRef, TableValuedExpression
  from evadb.parser.types import JoinType
  from evadb.utils.logging_manager import logger
label_desc: Use image node_id 13 for calling the TableSources obj's underlying member method code with example usage: obj.group_by_item(tree) and returns: expr