code: def _getInputValue(self, obj, fieldName):
      
      if isinstance(obj, dict):
        if not fieldName in obj:
          knownFields = ", ".join(
            key for key in obj.keys() if not key.startswith("_")
          )
          raise ValueError(
            "Unknown field name '%s' in input record. Known fields are '%s'.\n"
            "This could be because input headers are mislabeled, or because "
            "input data rows do not contain a value for '%s'." % (
              fieldName, knownFields, fieldName
            )
          )
        return obj[fieldName]
      else:
        return getattr(obj, fieldName)
docs: Gets the value of a given field from the input record