code: def fit_model(ts, sc=None):
      
      assert sc != None, "Missing SparkContext"
      
      jvm = sc._jvm
      jmodel = jvm.com.cloudera.sparkts.models.ARGARCH.fitModel(_py2java(sc, Vectors.dense(ts)))
      return ARGARCHModel(jmodel=jmodel, sc=sc)
docs: Fits an AR(1) + GARCH(1, 1) model to the given time series.
      
      Parameters
      ----------
      ts:
          the time series to which we want to fit a AR+GARCH model as a Numpy array
          
      Returns an ARGARCH model