code: def record_replace_field(rec, tag, new_field, field_position_global=None,
                           field_position_local=None):
      
      if field_position_global is None and field_position_local is None:
          raise InvenioBibRecordFieldError(
              "A field position is required to "
              "complete this operation.")
      elif field_position_global is not None and \
              field_position_local is not None:
          raise InvenioBibRecordFieldError(
              "Only one field position is required "
              "to complete this operation.")
      elif field_position_global:
          if tag not in rec:
              raise InvenioBibRecordFieldError("No tag '%s' in record." % tag)
  
          replaced = False
          for position, field in enumerate(rec[tag]):
              if field[4] == field_position_global:
                  rec[tag][position] = new_field
                  replaced = True
  
          if not replaced:
              raise InvenioBibRecordFieldError(
                  "No field has the tag '%s' and "
                  "the global field position '%d'." %
                  (tag, field_position_global))
      else:
          try:
              rec[tag][field_position_local] = new_field
          except KeyError:
              raise InvenioBibRecordFieldError("No tag '%s' in record." % tag)
          except IndexError:
              raise InvenioBibRecordFieldError(
                  "No field has the tag '%s' and "
                  "the local field position '%d'." % (tag, field_position_local))
docs: Replace a field with a new field.