anchor.diff:  field(Index, DataType, Length, Segment) ->
       ehl7_field:field(Index, DataType, Length, Segment).
   
  -
   -spec field(field_index(), raw_segment()) -> raw_field() | undefined.
   field(Index, Segment) ->
       ehl7_field:field(Index, Segment).
  
positive.code: segment(_SegmentId, [], _Repetition) ->
      undefined.
  
  -spec segment_count(raw_segment_id() | segment_id(), raw_msg() | msg()) -> non_neg_integer().
  segment_count(SegmentId, Msg) ->
      segment_count(SegmentId, Msg, 0).
  
negative.code: repetition(Index, DataType, Length, Segment) ->
      ehl7_field:repetition(Index, DataType, Length, Segment).
  
  -spec repetition(field_index(), raw_segment()) -> raw_field() | undefined.
  repetition(Index, Segment) ->
      ehl7_field:repetition(Index, Segment).
  