'Remove an alias'

@line_magic
def unalias(self, parameter_s=''):

    aname = parameter_s.strip()
    try:
        self.shell.alias_manager.undefine_alias(aname)
    except ValueError as e:
        print e
        return
    stored = self.shell.db.get('stored_aliases', {})
    if (aname in stored):
        print ('Removing    %stored    alias', aname)
        del stored[aname]
        self.shell.db['stored_aliases'] = stored
