'Handles Expr node and pick up a comment if string.'

def visit_Expr(self, node):

    if (isinstance(self.previous, ast.Assign) and isinstance(node.value, ast.Str)):
        try:
            varnames = get_lvar_names(self.previous.targets[0], self.get_self())
            for varname in varnames:
                if isinstance(node.value.s, text_type):
                    docstring = node.value.s
                else:
                    docstring = node.value.s.decode((self.encoding or 'utf-8'))
                self.add_variable_comment(varname, dedent_docstring(docstring))
                self.add_entry(varname)
        except TypeError:
            pass
