def previous_sibling(self):
stmts = self.parent.child_sequence(self)<EOL>index = stmts.index(self)<EOL>if index >= <NUM_LIT:1>:<EOL><INDENT>return stmts[index - <NUM_LIT:1>]<EOL><DEDENT>return None<EOL>
The previous sibling statement.

        :returns: The previous sibling statement node.
        :rtype: NodeNG or None