'Sets a value for each block in the given structure, using the given
data key.'

@classmethod
def _set_block_values(cls, block_structure, data_key):

    for block_key in block_structure.topological_traversal():
        block_structure.set_transformer_block_field(block_key, cls, data_key, cls._create_block_value(block_key, data_key))
