code: def pw_score_cosine(self, s1 : ClassId, s2 : ClassId) -> SimScore:
          
          df = self.assoc_df
          slice1 = df.loc[s1].values
          slice2 = df.loc[s2].values
          return 1 - cosine(slice1, slice2)
docs: Cosine similarity of two subjects
  
          Arguments
          ---------
          s1 : str
              class id
  
  
          Return
          ------
          number
              A number between 0 and 1