def _validate_arguments(self):
        """method to sanitize model parameters

        Parameters
        ---------
        None

        Returns
        -------
        None
        """
        # dtype
        if self.dtype not in ['numerical', 'categorical']:
            raise ValueError("dtype must be in ['numerical','categorical'], "\
                             "but found dtype = {}".format(self.dtype))

        # fit_linear XOR fit_splines
        if self.fit_linear == self.fit_splines:
            raise ValueError('term must have fit_linear XOR fit_splines, but found: '
                             'fit_linear= {}, fit_splines={}'.format(self.fit_linear, self.fit_splines))

        # penalties
        if not isiterable(self.penalties):
            self.penalties = [self.penalties]

        for i, p in enumerate(self.penalties):
            if not (hasattr(p, '__call__') or
                    (p in PENALTIES) or
                    (p is None)):
                raise ValueError("penalties must be callable or in "\
                                 "{}, but found {} for {}th penalty"\
                                 .format(list(PENALTIES.keys()), p, i))

        # check lams and distribute to penalites
        if not isiterable(self.lam):
            self.lam = [self.lam]

        for lam in self.lam:
            check_param(lam, param_name='lam', dtype='float', constraint='>= 0')

        if len(self.lam) == 1:
            self.lam = self.lam * len(self.penalties)

        if len(self.lam) != len(self.penalties):
            raise ValueError('expected 1 lam per penalty, but found '\
                             'lam = {}, penalties = {}'.format(self.lam, self.penalties))

        # constraints
        if not isiterable(self.constraints):
            self.constraints = [self.constraints]

        for i, c in enumerate(self.constraints):
            if not (hasattr(c, '__call__') or
                    (c in CONSTRAINTS) or
                    (c is None)):
                raise ValueError("constraints must be callable or in "\
                                 "{}, but found {} for {}th constraint"\
                                 .format(list(CONSTRAINTS.keys()), c, i))

        return self
method to sanitize model parameters

        Parameters
        ---------
        None

        Returns
        -------
        None