code: def getValues(self, suffixes=None):
          
          if suffixes is None:
              return DataFrame._fromDataFrameRef(self._impl.getValues())
          else:
              suffixes = list(map(str, suffixes))
              return DataFrame._fromDataFrameRef(
                  self._impl.getValuesLst(suffixes, len(suffixes))
              )
docs: If a list of suffixes is provided, get the specified suffixes value for
          all instances. Otherwise, get all the principal values of this entity.
          The specific returned value depends on the type of entity (see list
          below). For:
  
          - Variables and Objectives it returns the suffix ``val``.
          - Parameters it returns their values.
          - Constraints it returns the suffix ``dual``.
          - Sets it returns all the members of the set. Note that it does not
            apply to indexed sets. See :func:`~amplpy.Set.getValues`.
  
          Retruns:
              A :class:`~amplpy.DataFrame` containing the values for all
              instances.