code: def to_signed(cls, type_):
          
          if type_ in cls.unsigned:
              return {TYPE.ubyte: TYPE.byte_,
                      TYPE.uinteger: TYPE.integer,
                      TYPE.ulong: TYPE.long_}[type_]
          if type_ in cls.decimals or type_ in cls.signed:
              return type_
          return cls.unknown
docs: Return signed type or equivalent