code: def _get_first_header(dicom_directory):
      
      # looping over all files
      for root, _, file_names in os.walk(dicom_directory):
          # go over all the files and try to read the dicom header
          for file_name in file_names:
              file_path = os.path.join(root, file_name)
              # check wither it is a dicom file
              if not compressed_dicom.is_dicom_file(file_path):
                  continue
              # read the headers
              return compressed_dicom.read_file(file_path,
                                                stop_before_pixels=True,
                                                force=dicom2nifti.settings.pydicom_read_force)
      # no dicom files found
      raise ConversionError('NO_DICOM_FILES_FOUND')
docs: Function to get the first dicom file form a directory and return the header
      Useful to determine the type of data to convert
  
      :param dicom_directory: directory with dicom files