docs: def getPDT(typename):
      """get(typename) -> PrimitiveType
  
      Returns the PrimitiveType for typename or None.
      """
      if typename not in PrimitiveTypeMap and typename.startswith("S"):
          PrimitiveTypeMap[typename] = PrimitiveType(typename)
  
      return PrimitiveTypeMap.get(typename, None)