Fragment functions

experimental.import_10x_fragments(input, output)	Convert 10x fragment file to BPCells format
experimental.build_cell_groups(fragments, ...)	Build cell_groups array for use in pseudobulk_insertion_counts()
experimental.pseudobulk_insertion_counts(...)	Calculate a pseudobulk coverage matrix
experimental.precalculate_insertion_counts(...)	Precalculate per-base insertion counts from fragment data
experimental.PrecalculatedInsertionMatrix(path)	Disk-backed precalculated insertion matrix