Fits an AR(1) model to the given time series
    
    Parameters
    ----------
    ts:
        the time series to which we want to fit an autoregression model as a Numpy array
        
    Returns an ARModel

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