code: def visit_NameLeaf(self, item: NameLeaf) -> Set[str]:
      if item.value not in self.rules:
          return {item.value}
  
      if item.value not in self.first_sets:
          self.first_sets[item.value] = self.visit(
              self.rules[item.value]
          )
          return self.first_sets[item.value]
      elif item.value in self.in_process:
          return set()
  
      return self.first_sets[item.value]
  
imports: import argparse
  import pprint
  import sys
  from typing import Dict, Set
  from pegen.build import build_parser
  from pegen.grammar import Alt, Cut, Gather, GrammarVisitor, Group, Lookahead, NamedItem, NameLeaf, NegativeLookahead, Opt, Repeat0, Repeat1, Rhs, Rule, StringLeaf
  from pegen.parser_generator import compute_nullables
label_desc: Use image node_id 13 for calling the FirstSetCalculator obj's underlying member method code with example usage: obj.visit_NameLeaf(item) and returns: self, unknown, self, set