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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 visit_member(self, attribute_key, attribute, member_node, member_data, is_link_node, parent_data, index=None):
 """ Visits a member node in a resource data tree. :param tuple attribute_key: tuple containing the attribute tokens identifying the member node's position in the resource data tree. :param attribute: mapped attribute holding information about the member node's name (in the parent) and type etc. :type attribute: :class:`everest.representers.attributes.MappedAttribute` :param member_node: the node holding resource data. This is either a resource instance (when using a :class:`ResourceTreeTraverser` on a tree of resources) or a data element instance (when using a :class:`DataElementTreeTraverser` on a data element tree. :param dict member_data: dictionary holding all member data extracted during traversal (with mapped attributes as keys). :param bool is_link_node: indicates if the given member node is a link. :param dict parent_data: dictionary holding all parent data extracted during traversal (with mapped attributes as keys). :param int index: this indicates a member node's index in a collection parent node. If the parent node is a member node, it will be `None`. """

        raise NotImplementedError('Abstract method.')