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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 list(gandi, limit, step):
 """List operations."""

    output_keys = ['id', 'type', 'step']

    options = {
        'step': step,
        'items_per_page': limit,
        'sort_by': 'date_created DESC'
    }

    result = gandi.oper.list(options)
    for num, oper in enumerate(reversed(result)):
        if num:
            gandi.separator_line()
        output_generic(gandi, oper, output_keys)

    return result