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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def grok_for_node(element, default_vars):
 """Properly parses a For loop element"""

    if isinstance(element.iter, jinja2.nodes.Filter):
        if element.iter.name == 'default' \
           and element.iter.node.name not in default_vars:
            default_vars.append(element.iter.node.name)

        default_vars = default_vars + grok_vars(element)

    return default_vars