class_docstr: Gather all identifiers used throughout a node.
code: def visit_FunctionDef(self, node):
      self.result.add(node.name)
      self.generic_visit(node)
  
imports: from pythran.passmanager import NodeAnalysis
label_desc: Use image node_id 3 for calling the Identifiers obj's underlying member method code with example usage: obj.visit_FunctionDef(node) without return types