code: def delete_specimen(self, spec_name):
          
          specimen = self.find_by_name(spec_name, self.specimens)
          if not specimen:
              return False
          sample = specimen.sample
          if sample:
              sample.specimens.remove(specimen)
          self.specimens.remove(specimen)
          del specimen
          return []
docs: Remove specimen with name spec_name from self.specimens.
          If the specimen belonged to a sample, remove it from the sample's specimen list.