Add support for `in` operator

trans/transpiler/phases/emit_cpp/expr.py

@@ -156,6 +156,11 @@ class ExpressionVisitor(NodeVisitor):
         yield from self.visit_binary_operation(node.op, node.left, node.right)
 
     def visit_binary_operation(self, op, left: ast.AST, right: ast.AST) -> Iterable[str]:
+        if type(op) == ast.In:
+            call = ast.Call(ast.Attribute(right, "__contains__"), [left], [])
+            call.is_await = False
+            yield from self.visit_Call(call)
+            return
         op = SYMBOLS[type(op)]
         # TODO: handle precedence locally since only binops really need it
         # we could just store the history of traversed nodes and check if the last one was a binop