Find list of suitable donor cachments, ranked by hydrological similarity distance measure. This method is
        implicitly called when calling the :meth:`.growth_curve` method unless the attribute :attr:`.donor_catchments`
        is set manually.

        The results are stored in :attr:`.donor_catchments`. The (list of)
        :class:`floodestimation.entities.Catchment` will have an additional attribute :attr:`similarity_dist`.

        :param include_subject_catchment: - `auto`: include subject catchment if suitable for pooling and if urbext2000
                                            < 0.03
                                          - `force`: always include subject catchment
                                          - `exclude`: do not include the subject catchment
        :type include_subject_catchment: str

def find_donor_catchments(self, include_subject_catchment='auto'):
        """
        Find list of suitable donor cachments, ranked by hydrological similarity distance measure. This method is
        implicitly called when calling the :meth:`.growth_curve` method unless the attribute :attr:`.donor_catchments`
        is set manually.

        The results are stored in :attr:`.donor_catchments`. The (list of)
        :class:`floodestimation.entities.Catchment` will have an additional attribute :attr:`similarity_dist`.

        :param include_subject_catchment: - `auto`: include subject catchment if suitable for pooling and if urbext2000
                                            < 0.03
                                          - `force`: always include subject catchment
                                          - `exclude`: do not include the subject catchment
        :type include_subject_catchment: str
        """

        # Only if we have access to db with gauged catchment data
        if self.gauged_cachments:
            self.donor_catchments = self.gauged_cachments. \
                most_similar_catchments(subject_catchment=self.catchment,
                                        similarity_dist_function=lambda c1, c2: self._similarity_distance(c1, c2),
                                        include_subject_catchment=include_subject_catchment)
        else:
            self.donor_catchments = []