code: def collect_(self, node):
      names = set()
      for child in self.children(node):
          names.update(self.visit(child))
  
      if hasattr(node, "ctx"):
          if isinstance(node.ctx, _ast.Store):
              self.modified.update(names)
          elif isinstance(node.ctx, _ast.Load):
              self.used.update(names)
      return names
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from ...asttools import Visitor, visit_children
  import _ast
  from ...asttools.visitors.symbol_visitor import get_symbols
label_desc: Use image node_id 1 for calling a global function with example usage: collect_(node) and returns: names