check valid expr

check.py

import ast

def checkValid(expr: str):
    try:
        tree = ast.parse(expr)
    except:
        return False

    if len(tree.body) != 1:
        return False
        
    if not isinstance(tree.body[0], ast.Expr):
        return False

    def check(expr: ast.Expr):
        if isinstance(expr, (int, float)):
            return True

        if isinstance(expr, ast.Name):
            return True

        if isinstance(expr, ast.Constant):
            return check(expr.value)

        elif isinstance(expr, ast.BinOp):
            return check(expr.left) and check(expr.right)

        else:
            return False
    
    return check(tree.body[0].value)
    
assert checkValid("1") == True
assert checkValid("(1+2)*(x)") == True
assert checkValid('2**4') == True
assert checkValid('([]+1)') == False