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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 relation_call(method, relation_name=None, flag=None, state=None, *args):
 """Invoke a method on the class implementing a relation via the CLI"""

    if relation_name:
        relation = relation_from_name(relation_name)
        if relation is None:
            raise ValueError('Relation not found: %s' % relation_name)
    elif flag or state:
        relation = relation_from_flag(flag or state)
        if relation is None:
            raise ValueError('Relation not found: %s' % (flag or state))
    else:
        raise ValueError('Must specify either relation_name or flag')
    result = getattr(relation, method)(*args)
    if isinstance(relation, RelationBase) and method == 'conversations':
        # special case for conversations to make them work from CLI
        result = [c.scope for c in result]
    return result