def sort_all_slice_files_acquisition_time(files):
    """ Sort the DICOM files based on acquisition time.

    Args:
    ----
        files (list): List containing the pydicom datasets of the DICOM Files.

    Returns:
    -------
        slice_sorted_acq_time (list): List containing the file paths of the DICOM Files sorted by acquisition time.
    """
    slice_sorted_acq_time = []
    skipcount = 0
    for f in files: 
        if hasattr(f, 'AcquisitionTime'):
            slice_sorted_acq_time.append(f)
        else:
            skipcount = skipcount + 1
    print("skipped, no AcquisitionTime: {}".format(skipcount))

    return sorted(slice_sorted_acq_time, key=lambda s: s.AcquisitionTime)