def METHOD_NAME(paths):
    '''Load multiple hdf5 files to single numpy array.'''
    # Read data shapes.
    shape_map = defaultdict(lambda : (0, None))
    for p in paths:
        f = h5py.File(p, "r")
        for k in f.keys():
            shape = tuple(f[k].shape)
            shape_map[k] = (shape_map[k][0] + shape[0], shape[1])
        f.close()
    # Allocate output array.
    data_map = { k : np.empty(s, dtype="f4") for k, s in shape_map.items() }
    start_map = { k : 0 for k in shape_map }
    # Load files.
    for pi, p in enumerate(tqdm(paths, "load data")):
        f = h5py.File(p, "r")
        for k in f.keys():
            i0 = start_map[k]
            i1 = i0 + len(f[k])
            data_map[k][i0:i1] = f[k]
            start_map[k] += len(f[k])
        f.close()
    return data_map