'Change a `Column`\'s name.
Parameters
col_name : str
The current name of the column
new_name : str
The new name of the column'

def change_name(self, col_name, new_name):

    if ((new_name != col_name) and (new_name in self.names)):
        raise ValueError('New    name    {}    already    exists.'.format(new_name))
    else:
        self.change_attrib(col_name, 'name', new_name)
