'Visit a docstring statement which may have an assignment before.'

def visit_simple_stmt(self, node):

    if (node[0].type != token.STRING):
        return self.generic_visit(node)
    prev = node.get_prev_sibling()
    if (not prev):
        return
    if ((prev.type == sym.simple_stmt) and (prev[0].type == sym.expr_stmt) and (_eq in prev[0].children)):
        docstring = literals.evalString(node[0].value, self.encoding)
        docstring = prepare_docstring(docstring)
        self.add_docstring(prev[0], docstring)
