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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def from_df(cls, df):
 """Creates an OrbitPopulation from a DataFrame. :param df: :class:`pandas.DataFrame` object. Must contain the following columns: ``['M1','M2','P','ecc','mean_anomaly','obsx','obsy','obsz']``, i.e., as what is accessed via :attr:`OrbitPopulation.dataframe`. :return: :class:`OrbitPopulation`. """

        return cls(df['M1'], df['M2'], df['P'],
                   ecc=df['ecc'], mean_anomaly=df['mean_anomaly'],
                   obsx=df['obsx'], obsy=df['obsy'], obsz=df['obsz'])