SetComp

>>> print(ast.dump(
...     ast.parse('[x for x in numbers]', mode='eval'),
...     indent=4,
... ))
Expression(
    body=ListComp(
        elt=Name(id='x'),
        generators=[
            comprehension(
                target=Name(id='x', ctx=Store()),
                iter=Name(id='numbers'),
                is_async=0)]))
>>> print(ast.dump(
...     ast.parse('{x: x**2 for x in numbers}', mode='eval'),
...     indent=4,
... ))
Expression(
    body=DictComp(
        key=Name(id='x'),
        value=BinOp(
            left=Name(id='x'),
            op=Pow(),
            right=Constant(value=2)),
        generators=[
            comprehension(
                target=Name(id='x', ctx=Store()),
                iter=Name(id='numbers'),
                is_async=0)]))
>>> print(ast.dump(
...     ast.parse('{x for x in numbers}', mode='eval'),
...     indent=4,
... ))
Expression(
    body=SetComp(
        elt=Name(id='x'),
        generators=[
            comprehension(
                target=Name(id='x', ctx=Store()),
                iter=Name(id='numbers'),
                is_async=0)]))