How to use the elephant.current_source_density_src.basis_functions function in elephant

"""Places basis sources of the defined type.
        Checks if a given source_type is defined, if so then defines it
        self.basis, This function gives locations of the basis sources,
        Defines
        source_type : basis_fuctions.basis_1D.keys()
        self.R based on R_init
        self.dist_max as maximum distance between electrode and basis
        self.nsx = self.src_x.shape
        self.src_x : Locations at which basis sources are placed.
        Parameters
        ----------
        None
        """
        source_type = self.src_type
        try:
            self.basis = basis.basis_1D[source_type]
        except KeyError:
            raise KeyError('Invalid source_type for basis! available are:',
                           basis.basis_1D.keys())
        (self.src_x, self.R) = utils.distribute_srcs_1D(self.estm_x,
                                                        self.n_src_init,
                                                        self.ext_x,
                                                        self.R_init )
        self.n_src = self.src_x.size
        self.nsx = self.src_x.shape

Defines
        source_type : basis_fuctions.basis_2D.keys()
        self.R based on R_init
        self.dist_max as maximum distance between electrode and basis
        self.nsx, self.nsy, self.nsz = self.src_x.shape
        self.src_x, self.src_y, self.src_z : Locations at which basis sources are placed.
        Parameters
        ----------
        None
        """
        source_type = self.src_type
        try:
            self.basis = basis.basis_3D[source_type]
        except KeyError:
            raise KeyError('Invalid source_type for basis! available are:',
                           basis.basis_3D.keys())
        (self.src_x, self.src_y, self.src_z, self.R) = utils.distribute_srcs_3D(self.estm_x,
                                                                                self.estm_y,
                                                                                self.estm_z,
                                                                                self.n_src_init,
                                                                                self.ext_x,
                                                                                self.ext_y,
                                                                                self.ext_z,
                                                                                self.R_init)

        self.n_src = self.src_x.size
        self.nsx, self.nsy, self.nsz = self.src_x.shape

Defines
        source_type : basis_fuctions.basis_1D.keys()
        self.R based on R_init
        self.dist_max as maximum distance between electrode and basis
        self.nsx = self.src_x.shape
        self.src_x : Locations at which basis sources are placed.
        Parameters
        ----------
        None
        """
        source_type = self.src_type
        try:
            self.basis = basis.basis_1D[source_type]
        except KeyError:
            raise KeyError('Invalid source_type for basis! available are:',
                           basis.basis_1D.keys())
        (self.src_x, self.R) = utils.distribute_srcs_1D(self.estm_x,
                                                        self.n_src_init,
                                                        self.ext_x,
                                                        self.R_init )
        self.n_src = self.src_x.size
        self.nsx = self.src_x.shape

Defines
        source_type : basis_fuctions.basis_2D.keys()
        self.R based on R_init
        self.dist_max as maximum distance between electrode and basis
        self.nsx, self.nsy = self.src_x.shape
        self.src_x, self.src_y : Locations at which basis sources are placed.
        Parameters
        ----------
        None
        """
        source_type = self.src_type
        try:
            self.basis = basis.basis_2D[source_type]
        except KeyError:
            raise KeyError('Invalid source_type for basis! available are:',
                           basis.basis_2D.keys())
        (self.src_x, self.src_y, self.R) = utils.distribute_srcs_2D(self.estm_x,
                                                                    self.estm_y,
                                                                    self.n_src_init,
                                                                    self.ext_x,
                                                                    self.ext_y,
                                                                    self.R_init )
        self.n_src = self.src_x.size
        self.nsx, self.nsy = self.src_x.shape