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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 get_attribute(self, attribute: str) -> 'Node': """Returns the node representing the given attribute's value. Use only if is_mapping() returns true. Args: attribute: The name of the attribute to retrieve. Raises: KeyError: If the attribute does not exist. Returns: A node representing the value. """

        matches = [
            value_node for key_node, value_node in self.yaml_node.value
            if key_node.value == attribute
        ]
        if len(matches) != 1:
            raise SeasoningError(
                'Attribute not found, or found multiple times: {}'.format(
                    matches))
        return Node(matches[0])