code: def is_type_target(self):
          
          if self._is_type_target is None:
              #All we need to do is search through the custom types in the parent
              #module and see if any of their executables points to this method.
              self._is_type_target = False
              for tkey in self.module.types:
                  custype = self.module.types[tkey]
                  for execkey, execinst in custype.executables.items():
                      if execinst.target is self:
                          self._is_type_target = custype
                          break
                  if self._is_type_target:
                      break
  
          return self._is_type_target
docs: Returns the CustomType instance if this executable is an embedded 
          procedure in a custom type declaration; else False.