Update utils.py

tests/python_package_test/utils.py

@@ -1,23 +1,7 @@
 # coding: utf-8
-import sklearn.datasets
+from functools import lru_cache
 
-try:
-    from functools import lru_cache
-except ImportError:
-    import warnings
-    warnings.warn("Could not import functools.lru_cache", RuntimeWarning)
-
-    def lru_cache(maxsize=None):
-        cache = {}
-
-        def _lru_wrapper(user_function):
-            def wrapper(*args, **kwargs):
-                arg_key = (args, tuple(kwargs.items()))
-                if arg_key not in cache:
-                    cache[arg_key] = user_function(*args, **kwargs)
-                return cache[arg_key]
-            return wrapper
-        return _lru_wrapper
+import sklearn.datasets
 
 
 @lru_cache(maxsize=None)