add minimal verifiers example (#472)

examples/verifiers/vf_rg.py

@@ -0,0 +1,36 @@
+"""Example training script for using the Reasoning Gym environment in verifiers."""
+
+import verifiers as vf
+from verifiers.envs.reasoninggym_env import ReasoningGymEnv
+
+model_name = f"Qwen/Qwen2.5-1.5B-Instruct"
+model, tokenizer = vf.get_model_and_tokenizer(model_name)
+
+vf_env = ReasoningGymEnv(
+    gym=[
+        "basic_arithmetic",
+        "bitwise_arithmetic",
+        "decimal_arithmetic",
+    ],
+    num_samples=100,
+    num_eval_samples=50,
+    max_concurrent=100,
+)
+
+training_args = vf.grpo_defaults(run_name="reasoning-gym-test")
+training_args.num_iterations = 1
+training_args.per_device_train_batch_size = 4
+training_args.num_generations = 8
+training_args.gradient_accumulation_steps = 4
+training_args.max_prompt_length = 1024
+training_args.max_completion_length = 4096
+training_args.max_steps = 100
+
+trainer = vf.GRPOTrainer(
+    model=model,
+    processing_class=tokenizer,
+    env=vf_env,
+    args=training_args,
+)
+
+trainer.train()