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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 _param_fields(kwargs, fields):
 """ Normalize the "fields" argument to most find methods """

  if fields is None:
    return
  if type(fields) in [list, set, frozenset, tuple]:
    fields = {x: True for x in fields}
  if type(fields) == dict:
    fields.setdefault("_id", False)
  kwargs["projection"] = fields