Convert a "wide" SArray to one or two "tall" columns in an SFrame by
        stacking all values.

        The stack works only for columns of dict, list, or array type.  If the
        column is dict type, two new columns are created as a result of
        stacking: one column holds the key and another column holds the value.
        The rest of the columns are repeated for each key/value pair.

        If the column is array or list type, one new column is created as a
        result of stacking. With each row holds one element of the array or list
        value, and the rest columns from the same original row repeated.

        The returned SFrame includes the newly created column(s).

        Parameters
        --------------
        new_column_name : str | list of str, optional
            The new column name(s). If original column is list/array type,
            new_column_name must a string. If original column is dict type,
            new_column_name must be a list of two strings. If not given, column
            names are generated automatically.

        drop_na : boolean, optional
            If True, missing values and empty list/array/dict are all dropped
            from the resulting column(s). If False, missing values are
            maintained in stacked column(s).

        new_column_type : type | list of types, optional
            The new column types. If original column is a list/array type
            new_column_type must be a single type, or a list of one type. If
            original column is of dict type, new_column_type must be a list of
            two types. If not provided, the types are automatically inferred
            from the first 100 values of the SFrame.

        Returns
        -------
        out : SFrame
            A new SFrame that contains the newly stacked column(s).

        Examples
        ---------
        Suppose 'sa' is an SArray of dict type:

        >>> sa = turicreate.SArray([{'a':3, 'cat':2},
        ...                         {'a':1, 'the':2},
        ...                         {'the':1, 'dog':3},
        ...                         {}])
        [{'a': 3, 'cat': 2}, {'a': 1, 'the': 2}, {'the': 1, 'dog': 3}, {}]

        Stack would stack all keys in one column and all values in another
        column:

        >>> sa.stack(new_column_name=['word', 'count'])
        +------+-------+
        | word | count |
        +------+-------+
        |  a   |   3   |
        | cat  |   2   |
        |  a   |   1   |
        | the  |   2   |
        | the  |   1   |
        | dog  |   3   |
        | None |  None |
        +------+-------+
        [7 rows x 2 columns]

        Observe that since topic 4 had no words, an empty row is inserted.
        To drop that row, set drop_na=True in the parameters to stack.

def stack(self, new_column_name=None, drop_na=False, new_column_type=None):
        """
        Convert a "wide" SArray to one or two "tall" columns in an SFrame by
        stacking all values.

        The stack works only for columns of dict, list, or array type.  If the
        column is dict type, two new columns are created as a result of
        stacking: one column holds the key and another column holds the value.
        The rest of the columns are repeated for each key/value pair.

        If the column is array or list type, one new column is created as a
        result of stacking. With each row holds one element of the array or list
        value, and the rest columns from the same original row repeated.

        The returned SFrame includes the newly created column(s).

        Parameters
        --------------
        new_column_name : str | list of str, optional
            The new column name(s). If original column is list/array type,
            new_column_name must a string. If original column is dict type,
            new_column_name must be a list of two strings. If not given, column
            names are generated automatically.

        drop_na : boolean, optional
            If True, missing values and empty list/array/dict are all dropped
            from the resulting column(s). If False, missing values are
            maintained in stacked column(s).

        new_column_type : type | list of types, optional
            The new column types. If original column is a list/array type
            new_column_type must be a single type, or a list of one type. If
            original column is of dict type, new_column_type must be a list of
            two types. If not provided, the types are automatically inferred
            from the first 100 values of the SFrame.

        Returns
        -------
        out : SFrame
            A new SFrame that contains the newly stacked column(s).

        Examples
        ---------
        Suppose 'sa' is an SArray of dict type:

        >>> sa = turicreate.SArray([{'a':3, 'cat':2},
        ...                         {'a':1, 'the':2},
        ...                         {'the':1, 'dog':3},
        ...                         {}])
        [{'a': 3, 'cat': 2}, {'a': 1, 'the': 2}, {'the': 1, 'dog': 3}, {}]

        Stack would stack all keys in one column and all values in another
        column:

        >>> sa.stack(new_column_name=['word', 'count'])
        +------+-------+
        | word | count |
        +------+-------+
        |  a   |   3   |
        | cat  |   2   |
        |  a   |   1   |
        | the  |   2   |
        | the  |   1   |
        | dog  |   3   |
        | None |  None |
        +------+-------+
        [7 rows x 2 columns]

        Observe that since topic 4 had no words, an empty row is inserted.
        To drop that row, set drop_na=True in the parameters to stack.
        """
        from .sframe import SFrame as _SFrame
        return _SFrame({'SArray': self}).stack('SArray',
                                               new_column_name=new_column_name,
                                               drop_na=drop_na,
                                               new_column_type=new_column_type)