How to use the anndata.read_mtx function in anndata

logg.debug(f'reading {filename}')
    if not cache and not suppress_cache_warning:
        logg.hint(
            'This might be very slow. Consider passing `cache=True`, '
            'which enables much faster reading from a cache file.'
        )
    # do the actual reading
    if ext == 'xlsx' or ext == 'xls':
        if sheet is None:
            raise ValueError(
                "Provide `sheet` parameter when reading '.xlsx' files."
            )
        else:
            adata = read_excel(filename, sheet)
    elif ext in {'mtx', 'mtx.gz'}:
        adata = read_mtx(filename)
    elif ext == 'csv':
        adata = read_csv(filename, first_column_names=first_column_names)
    elif ext in {'txt', 'tab', 'data', 'tsv'}:
        if ext == 'data':
            logg.hint(
                "... assuming '.data' means tab or white-space "
                'separated text file',
            )
            logg.hint('change this by passing `ext` to sc.read')
        adata = read_text(filename, delimiter, first_column_names)
    elif ext == 'soft.gz':
        adata = _read_softgz(filename)
    elif ext == 'loom':
        adata = read_loom(filename=filename, **kwargs)
    else:
        raise ValueError(f'Unknown extension {ext}.')