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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 op_get_mutate_fields( op_name ):
 """ Get the names of the fields that will change when this operation gets applied to a record. """

    global MUTATE_FIELDS

    if op_name not in MUTATE_FIELDS.keys():
        raise Exception("No such operation '%s'" % op_name)

    fields = MUTATE_FIELDS[op_name][:]
    return fields