Get Access to string functions.

        Returns
        -------
        StringMethods

        Examples
        --------
        >>> sr = bl.Series([b' aB ', b'GoOsfrABA'])
        >>> print(sr.str.lower().evaluate())
        <BLANKLINE>
        ---  ---------
          0   ab
          1  goosfraba

def str(self):
        """Get Access to string functions.

        Returns
        -------
        StringMethods

        Examples
        --------
        >>> sr = bl.Series([b' aB ', b'GoOsfrABA'])
        >>> print(sr.str.lower().evaluate())
        <BLANKLINE>
        ---  ---------
          0   ab
          1  goosfraba

        """
        if self.dtype.char != 'S':
            raise AttributeError('Can only use .str when data is of type np.bytes_')

        from .strings import StringMethods

        return StringMethods(self)