How to use the pdpipe.col_generation.ApplyByCols function in pdpipe

def test_applybycols_with_drop():
    """Testing ApplyByCols pipeline stages."""
    df = ph_df()
    round_ph = ApplyByCols("ph", math.ceil, drop=False)
    res_df = round_ph(df)
    assert 'ph' in res_df.columns
    assert 'ph_app' in res_df.columns
    assert res_df.columns.get_loc('ph') == 0
    assert res_df.columns.get_loc('ph_app') == 1
    assert res_df['ph_app'][1] == 4
    assert res_df['ph_app'][2] == 8
    assert res_df['ph_app'][3] == 13

def test_applybycols_with_result_columns():
    """Testing ApplyByCols pipeline stages."""
    df = ph_df()
    round_ph = ApplyByCols("ph", math.ceil, result_columns='round_ph')
    res_df = round_ph(df)
    assert 'ph' not in res_df.columns
    assert res_df.columns.get_loc('round_ph') == 0
    assert res_df['round_ph'][1] == 4
    assert res_df['round_ph'][2] == 8
    assert res_df['round_ph'][3] == 13

def test_applybycols_with_bad_len_result_columns():
    """Testing ApplyByCols pipeline stages."""
    with pytest.raises(ValueError):
        ApplyByCols("ph", math.ceil, result_columns=['a', 'b'])

def test_applybycols_func_desc():
    """Testing ApplyByCols pipeline stages."""
    df = ph_df()
    round_ph = ApplyByCols("ph", math.ceil, func_desc='Round PH values')
    res_df = round_ph(df)
    assert res_df.columns.get_loc('ph') == 0
    assert res_df['ph'][1] == 4
    assert res_df['ph'][2] == 8
    assert res_df['ph'][3] == 13

def test_applybycols():
    """Testing ApplyByCols pipeline stages."""
    df = ph_df()
    round_ph = ApplyByCols("ph", math.ceil)
    res_df = round_ph(df)
    assert res_df.columns.get_loc('ph') == 0
    assert res_df['ph'][1] == 4
    assert res_df['ph'][2] == 8
    assert res_df['ph'][3] == 13

else:
                self._result_columns = [col + suffix for col in self._columns]
        else:
            self._result_columns = _interpret_columns_param(result_columns)
            if len(self._result_columns) != len(self._columns):
                raise ValueError(
                    "columns and result_columns parameters must"
                    " be string lists of the same length!"
                )
        self._drop = drop
        if func_desc is None:
            func_desc = ""
        self._func_desc = func_desc
        col_str = _list_str(self._columns)
        sfx = "s" if len(self._columns) > 1 else ""
        base_str = ApplyByCols._BASE_STR.format(self._func_desc, sfx, col_str)
        super_kwargs = {
            "exmsg": base_str + ApplyByCols._DEF_EXC_MSG_SUFFIX,
            "appmsg": base_str + ApplyByCols._DEF_APP_MSG_SUFFIX,
            "desc": base_str + ApplyByCols._DEF_DESCRIPTION_SUFFIX,
        }
        super_kwargs.update(**kwargs)
        super().__init__(**super_kwargs)

self._result_columns = _interpret_columns_param(result_columns)
            if len(self._result_columns) != len(self._columns):
                raise ValueError(
                    "columns and result_columns parameters must"
                    " be string lists of the same length!"
                )
        self._drop = drop
        if func_desc is None:
            func_desc = ""
        self._func_desc = func_desc
        col_str = _list_str(self._columns)
        sfx = "s" if len(self._columns) > 1 else ""
        base_str = ApplyByCols._BASE_STR.format(self._func_desc, sfx, col_str)
        super_kwargs = {
            "exmsg": base_str + ApplyByCols._DEF_EXC_MSG_SUFFIX,
            "appmsg": base_str + ApplyByCols._DEF_APP_MSG_SUFFIX,
            "desc": base_str + ApplyByCols._DEF_DESCRIPTION_SUFFIX,
        }
        super_kwargs.update(**kwargs)
        super().__init__(**super_kwargs)

if len(self._result_columns) != len(self._columns):
                raise ValueError(
                    "columns and result_columns parameters must"
                    " be string lists of the same length!"
                )
        self._drop = drop
        if func_desc is None:
            func_desc = ""
        self._func_desc = func_desc
        col_str = _list_str(self._columns)
        sfx = "s" if len(self._columns) > 1 else ""
        base_str = ApplyByCols._BASE_STR.format(self._func_desc, sfx, col_str)
        super_kwargs = {
            "exmsg": base_str + ApplyByCols._DEF_EXC_MSG_SUFFIX,
            "appmsg": base_str + ApplyByCols._DEF_APP_MSG_SUFFIX,
            "desc": base_str + ApplyByCols._DEF_DESCRIPTION_SUFFIX,
        }
        super_kwargs.update(**kwargs)
        super().__init__(**super_kwargs)

else:
            self._result_columns = _interpret_columns_param(result_columns)
            if len(self._result_columns) != len(self._columns):
                raise ValueError(
                    "columns and result_columns parameters must"
                    " be string lists of the same length!"
                )
        self._drop = drop
        if func_desc is None:
            func_desc = ""
        self._func_desc = func_desc
        col_str = _list_str(self._columns)
        sfx = "s" if len(self._columns) > 1 else ""
        base_str = ApplyByCols._BASE_STR.format(self._func_desc, sfx, col_str)
        super_kwargs = {
            "exmsg": base_str + ApplyByCols._DEF_EXC_MSG_SUFFIX,
            "appmsg": base_str + ApplyByCols._DEF_APP_MSG_SUFFIX,
            "desc": base_str + ApplyByCols._DEF_DESCRIPTION_SUFFIX,
        }
        super_kwargs.update(**kwargs)
        super().__init__(**super_kwargs)