code: def idfstr(self):
          
          if self.outputtype == 'standard':
              astr = ''
          else:
              astr = self.model.__repr__()
  
          if self.outputtype == 'standard':
              astr = ''
              dtls = self.model.dtls
              for objname in dtls:
                  for obj in self.idfobjects[objname]:
                      astr = astr + obj.__repr__()
          elif self.outputtype == 'nocomment':
              return astr
          elif self.outputtype == 'nocomment1':
              slist = astr.split('\n')
              slist = [item.strip() for item in slist]
              astr = '\n'.join(slist)
          elif self.outputtype == 'nocomment2':
              slist = astr.split('\n')
              slist = [item.strip() for item in slist]
              slist = [item for item in slist if item != '']
              astr = '\n'.join(slist)
          elif self.outputtype == 'compressed':
              slist = astr.split('\n')
              slist = [item.strip() for item in slist]
              astr = ' '.join(slist)
          else:
              raise ValueError("%s is not a valid outputtype" % self.outputtype)
          return astr
docs: String representation of the IDF.
  
          Returns
          -------
          str