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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _is_singleframe_4d(dicom_input):
 """ Use this function to detect if a dicom series is a philips singleframe 4D dataset """

    header = dicom_input[0]

    # check if there are stack information
    slice_number_mr_tag = Tag(0x2001, 0x100a)
    if slice_number_mr_tag not in header:
        return False

    # check if there are multiple timepoints
    grouped_dicoms = _get_grouped_dicoms(dicom_input)
    if len(grouped_dicoms) <= 1:
        return False

    return True