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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 expand_valid_values(valid_values):
 """Expand supported playbook variables to their full list. Args: valid_values (list):
 The list of valid values for Choice or MultiChoice inputs. Returns: List: An expanded list of valid values for Choice or MultiChoice inputs. """


        if '${GROUP_TYPES}' in valid_values:
            valid_values.remove('${GROUP_TYPES}')
            valid_values.extend(
                [
                    'Adversary',
                    'Campaign',
                    'Document',
                    'Email',
                    'Event',
                    'Incident',
                    'Intrusion Set',
                    'Signature',
                    'Task',
                    'Threat',
                ]
            )
        elif '${OWNERS}' in valid_values:
            valid_values.remove('${OWNERS}')
            valid_values.append('')
        elif '${USERS}' in valid_values:
            valid_values.remove('${USERS}')
            valid_values.append('')
        return valid_values