Add bytearray.append

Author: lili668668

tests/snippets/bytearray.py

@@ -65,3 +65,9 @@
     pass
 else:
     assert False
+
+a = bytearray(b'appen')
+assert len(a) == 5
+a.append(100)
+assert len(a) == 6
+assert a.pop() == 100

vm/src/obj/objbytearray.rs

@@ -79,6 +79,7 @@ pub fn init(context: &PyContext) {
         "istitle" =>context.new_rustfunc(PyByteArrayRef::istitle),
         "isupper" => context.new_rustfunc(PyByteArrayRef::isupper),
         "lower" => context.new_rustfunc(PyByteArrayRef::lower),
+        "append" => context.new_rustfunc(PyByteArrayRef::append),
         "pop" => context.new_rustfunc(PyByteArrayRef::pop),
         "upper" => context.new_rustfunc(PyByteArrayRef::upper)
     });
@@ -213,6 +214,10 @@ impl PyByteArrayRef {
         self.value.borrow_mut().clear();
     }
 
+    fn append(self, x: u8, _vm: &VirtualMachine) {
+        self.value.borrow_mut().push(x);
+    }
+
     fn pop(self, vm: &VirtualMachine) -> PyResult<u8> {
         let mut bytes = self.value.borrow_mut();
         bytes