def get_funct(sk_model):

    """
    It returns the activation fucntion of the model.
    
    Parameters
    ----------
    model :
        A Scikit-learn model instance.

    Returns
    -------
    a_fn : String
        Returns the activation function.

    """
    a_fn = sk_model.activation
    if a_fn =='relu':
        a_fn = 'rectifier'
    return a_fn