I am having hard time finding equivalent to atomic type in Maple to use in Sage for converting a function written in Maple to sagemath.

Here is description of what an atomic type is. Examples will make it more clear

```
type(1,'atomic');
true
type(1/2,'atomic');
true
type(.5,'atomic');
true
type(3+1/2*I,'atomic');
true
type(x+1/2*I,'atomic');
false
type("String",'atomic');
true
type(Name,'atomic');
true
type(a[b],'atomic');
true
type(a/b,'atomic');
false
```

In Mathematica, this is called AtomQ " yields True if expr is an expression which cannot be divided into subexpressions, and yields False otherwise."

Now, in sympy, the closest I found is `is_Atom`

even though it is not exactly the same as Maple and Mathematica. In sagemath, the closest I found is `expression.is_symbol()`

but this is also not exactly the same.

My question is, how does one check expression is atomic in sagemath? I googled and not able to find such command. I am sure it is there somewhere since this basic command.

Thank you --Nasser