这个函数可以快速实现1维池化层
各参数及返回值：
Arguments:
inputs: The tensor over which to pool. Must have rank 3.
pool_size: An integer or tuple/list of a single integer,
representing the size of the pooling window.
strides: An integer or tuple/list of a single integer, specifying the
strides of the pooling operation.
padding: A string. The padding method, either 'valid' or 'same'.
Case-insensitive.
data_format: A string, one of `channels_last` (default) or `channels_first`.
The ordering of the dimensions in the inputs.
`channels_last` corresponds to inputs with shape
`(batch, length, channels)` while `channels_first` corresponds to
inputs with shape `(batch, channels, length)`.
name: A string, the name of the layer.
Returns:
The output tensor, of rank 3.
实验：
以上实验参数：batch_size = 2, seq_len = 3, embed=1
