'Deserializes and returns the block structure starting at
root_block_usage_key from the given store, if it\'s found in the store.
The given root_block_usage_key must equate the root_block_usage_key
previously passed to serialize_to_cache.
Arguments:
root_block_usage_key (UsageKey) - The usage_key for the root
of the block structure that is to be deserialized from
the given cache.
block_structure_store (BlockStructureStore) - The
store from which the block structure is to be
deserialized.
Returns:
BlockStructure - The deserialized block structure starting
at root_block_usage_key, if found in the cache.
Raises:
BlockStructureNotFound - If the root_block_usage_key is not found
in the store.'

@classmethod
def create_from_store(cls, root_block_usage_key, block_structure_store):

    return block_structure_store.get(root_block_usage_key)
