def _sparse_blockify(tuples, dtype=None):
new_blocks = []<EOL>for i, names, array in tuples:<EOL><INDENT>array = _maybe_to_sparse(array)<EOL>block = make_block(array, placement=[i])<EOL>new_blocks.append(block)<EOL><DEDENT>return new_blocks<EOL>
return an array of blocks that potentially have different dtypes (and
    are sparse)