code: def visit_fields(self, node, visited_children):
      first, rest = visited_children
      return [first] + [field for comma, field in rest]
  
imports: from parsimonious import Grammar, NodeVisitor
  from hail.expr.nat import NatVariable
  from .None import types
  from hail.utils.java import unescape_parsable
label_desc: Use image node_id 13 for calling the VCFTypeConstructor obj's underlying member method code with example usage: obj.visit_fields(node, visited_children) and returns: unknown