[CodeStyle][py2] Clean up all usages of six package and __future__ imports in docs

ci_scripts/Dockerfile

@@ -28,7 +28,6 @@ pytest' >requirements && \
 RUN echo 'Pillow\n\
 numpy\n\
 gast==0.3.3\n\
-six\n\
 protobuf\n\
 urllib3\n\
 certifi\n\

ci_scripts/check_api_parameters.py

@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function
 import json
 import argparse
 import os.path as osp
@@ -51,8 +50,11 @@ def parse_args():
     parser = argparse.ArgumentParser(description='check api parameters')
     parser.add_argument('--debug', dest='debug', action="store_true")
     for item in arguments:
-        parser.add_argument(
-            item[0], dest=item[1], help=item[4], type=item[2], default=item[3])
+        parser.add_argument(item[0],
+                            dest=item[1],
+                            help=item[4],
+                            type=item[2],
+                            default=item[3])
 
     args = parser.parse_args()
     return args

ci_scripts/check_pr_approval.py

@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function
 import sys
 import json
 

docs/api/paddle/static/Program_cn.rst

@@ -122,24 +122,21 @@ Program，当 ``for_test=True`` 时返回一个新的、仅包含当前 Program
 
 .. code-block:: python
 
-    import six
-
     def print_prog(prog):
-        for name, value in sorted(six.iteritems(prog.block(0).vars)):
+        for name, value in sorted(prog.block(0).vars.items()):
             print(value)
         for op in prog.block(0).ops:
             print("op type is {}".format(op.type))
             print("op inputs are {}".format(op.input_arg_names))
             print("op outputs are {}".format(op.output_arg_names))
-            for key, value in sorted(six.iteritems(op.all_attrs())):
+            for key, value in sorted(op.all_attrs().items()):
                 if key not in ['op_callstack', 'op_role_var']:
                     print(" [ attrs: {}:   {} ]".format(key, value))
 
 1. 克隆一个 Program，示例代码如下。
 
 .. code-block:: python
 
-    import six
     import paddle
     import paddle.static as static
     import paddle.utils as utils
@@ -148,13 +145,13 @@ Program，当 ``for_test=True`` 时返回一个新的、仅包含当前 Program
     paddle.enable_static()
 
     def print_prog(prog):
-        for name, value in sorted(six.iteritems(prog.block(0).vars)):
+        for name, value in sorted(prog.block(0).vars.items()):
             print(value)
         for op in prog.block(0).ops:
             print("op type is {}".format(op.type))
             print("op inputs are {}".format(op.input_arg_names))
             print("op outputs are {}".format(op.output_arg_names))
-            for key, value in sorted(six.iteritems(op.all_attrs())):
+            for key, value in sorted(op.all_attrs().items()):
                 if key not in ['op_callstack', 'op_role_var']:
                     print(" [ attrs: {}:   {} ]".format(key, value))
 
@@ -192,7 +189,6 @@ Program，当 ``for_test=True`` 时返回一个新的、仅包含当前 Program
 
 .. code-block:: python
 
-    import six
     import paddle
     import paddle.static as static
     import paddle.utils as utils
@@ -201,13 +197,13 @@ Program，当 ``for_test=True`` 时返回一个新的、仅包含当前 Program
     paddle.enable_static()
 
     def print_prog(prog):
-        for name, value in sorted(six.iteritems(prog.block(0).vars)):
+        for name, value in sorted(prog.block(0).vars.items()):
             print(value)
         for op in prog.block(0).ops:
             print("op type is {}".format(op.type))
             print("op inputs are {}".format(op.input_arg_names))
             print("op outputs are {}".format(op.output_arg_names))
-            for key, value in sorted(six.iteritems(op.all_attrs())):
+            for key, value in sorted(op.all_attrs().items()):
                 if key not in ['op_callstack', 'op_role_var']:
                     print(" [ attrs: {}:   {} ]".format(key, value))
 

docs/api/paddle/static/nn/multi_box_head_cn.rst

@@ -25,7 +25,7 @@ multi_box_head
                   min_sizes = []
                   max_sizes = []
                   step = int(math.floor(((max_ratio - min_ratio)) / (num_layer - 2)))
-                  for ratio in six.moves.range(min_ratio, max_ratio + 1, step):
+                  for ratio in range(min_ratio, max_ratio + 1, step):
                       min_sizes.append(base_size * ratio / 100.)
                       max_sizes.append(base_size * (ratio + step) / 100.)
                       min_sizes = [base_size * .10] + min_sizes

docs/api/paddle/static/py_func_cn.rst

@@ -40,7 +40,6 @@ Tensor|tuple(Tensor)|list[Tensor]，前向函数的输出 ``out``
 .. code-block:: python
 
     import paddle
-    import six
     import numpy as np
 
     paddle.enable_static()
@@ -64,7 +63,7 @@ Tensor|tuple(Tensor)|list[Tensor]，前向函数的输出 ``out``
 
     def simple_net(img, label):
         hidden = img
-        for idx in six.moves.range(4):
+        for idx in range(4):
             hidden = paddle.static.nn.fc(hidden, size=200)
             new_hidden = create_tmp_var(name='hidden_{}'.format(idx),
                 dtype=hidden.dtype, shape=hidden.shape)

docs/guides/06_distributed_training/cluster_quick_start_en.rst

@@ -33,7 +33,6 @@ tasks through different startup commands.
 
 .. code-block:: python
 
-    from __future__ import print_function
     from args import parse_args
     import os
     import sys

docs/guides/model_convert/update_cn.md

@@ -367,8 +367,6 @@ $ python -m paddle.distributed.launch train.py
 launch 方式启动训练，以文件为单位启动多进程，需要在启动时调用 ``paddle.distributed.launch`` ，对于进程的管理要求较高。飞桨框架 2.0 版本增加了 ``spawn`` 启动方式，可以更好地控制进程，在日志打印、训练退出时更友好。使用示例如下：
 
 ```python
-from __future__ import print_function
-
 import paddle
 import paddle.nn as nn
 import paddle.optimizer as opt

docs/guides/model_convert/update_en.md

@@ -368,8 +368,6 @@ $ python -m paddle.distributed.launch train.py
 Launch method need to start multiple processes as a file. You need to call ``paddle.distributed.launch`` at launch time with a higher process management requirements. PaddlePaddle framework 2.0 added ``spawn`` launch method, for better controlling the process and more friendly in the log printing and training exit. Usage examples are as follows.
 
 ```python
-from __future__ import print_function
-
 import paddle
 import paddle.nn as nn
 import paddle.optimizer as opt
@@ -435,8 +433,6 @@ if __name__ == '__main__':
 # {0,1,2,3,4,5,6,7}, but you do not have the right to configure CUDA_VISIBLE_DEVICES, then you can
 # Specify the parameter selected_gpus to select the card you wish to use, e.g. selected_gpus='4,5'.
 # You can specify the use of card #4 and card #5
-
-Translated with www.DeepL.com/Translator (free version)
 if __name__ == '__main__':
     dist.spawn(train, nprocs=2, selected_gpus='4,5')
 

docs/install/FAQ.md

@@ -5,10 +5,6 @@
 
     > 请[安装 nccl2](https://developer.nvidia.com/nccl/nccl-download)
 
-- 报错`Cannot uninstall 'six'.`
-
-    > 此问题可能与系统中已有 Python 有关，请使用`pip install paddlepaddle --ignore-installed six`（CPU）或`pip install paddlepaddle --ignore-installed six`（GPU）解决
-
 - CentOS6 下如何编译 python2.7 为共享库?
 
     > 使用以下指令：

docs/practices/gan/dcgan_face/dcgan_face.ipynb

@@ -201,7 +201,6 @@
     "import time\n",
     "import paddle\n",
     "from paddle.io import Dataset\n",
-    "import six\n",
     "from PIL import Image as PilImage\n",
     "from paddle.static import InputSpec\n",
     "paddle.enable_static()\n",