@classmethod
def from_regression(cls, clock_model):
    """
        Create the conversion object automatically from the tree

        Parameters
        ----------

         clock_model : dict
            dictionary as returned from TreeRegression with fields intercept and slope

        """
    dc = cls()
    dc.clock_rate = clock_model['slope']
    dc.intercept = clock_model['intercept']
    dc.chisq = clock_model['chisq'] if 'chisq' in clock_model else None
    dc.valid_confidence = clock_model['valid_confidence'
        ] if 'valid_confidence' in clock_model else False
    if 'cov' in clock_model and dc.valid_confidence:
        dc.cov = clock_model['cov']
    dc.r_val = clock_model['r_val']
    return dc
