message: Add api documentation for `tf.io.gfile.GFile`.
diff: @@ -39,7 +39,7 @@ from tensorflow.python.util.tf_export import tf_export
  @tf_export('io.gfile.GFile', v1=['gfile.GFile', 'gfile.Open', 'io.gfile.GFile'])
  class GFile(_FileIO):
  - """File I/O wrappers without thread locking.
  + r"""File I/O wrappers without thread locking.
  The main roles of the `tf.io.gfile` module are:
  @@ -56,8 +56,62 @@ class GFile(_FileIO):
  *Note*: though similar to Python's I/O implementation, there are semantic
  differences to make `tf.io.gfile` more efficient for backing filesystems. For
  - example, a write mode file will not be opened until the first write call, to
  + example, a write mode file will not be opened until the first write call to
  minimize RPC invocations in network filesystems.
  +
  + Once you obtain a `GFile` object, you can use it in most ways as you would any
  + Python's file object:
  +
  + >>> with open("/tmp/x", "w") as f:
  + ... f.write("asdf")
  + 4
  + >>> with tf.io.gfile.GFile("/tmp/x") as f:
  + ... f.read()
  + 'asdf'
  +
  + The difference is that you can specify URI schemes to use other filesystems
  + (e.g., `gs://` for GCS, `s3://` for S3, etc.), if they are supported. Using
  + `file://` as an example, we have:
  +
  + >>> with tf.io.gfile.GFile("file:///tmp/x", "w") as f:
  + ... f.write("qwert")
  + ... f.write("asdf")
  + >>> tf.io.gfile.GFile("file:///tmp/x").read()
  + 'qwertasdf'
  +
  + You can also read all lines of a file directly:
  +
  + >>> with tf.io.gfile.GFile("file:///tmp/x", "w") as f:
  + ... f.write("asdf\n")
  + ... f.write("qwer\n")
  + >>> tf.io.gfile.GFile("/tmp/x").readlines()
  + ['asdf\n', 'qwer\n']
  +
  + You can iterate over the lines:
  +
  + >>> with tf.io.gfile.GFile("file:///tmp/x", "w") as f:
  + ... f.write("asdf\n")
  + ... f.write("qwer\n")
  + >>> for line in tf.io.gfile.GFile("/tmp/x"):
  + ... print(line[:-1]) # removes the end of line character
  + asdf
  + qwer
  +
  + Random access read is possible if the underlying filesystem supports it:
  +
  + >>> with open("/tmp/x", "w") as f:
  + ... f.write("asdfqwer")
  + >>> f = tf.io.gfile.GFile("/tmp/x")
  + >>> f.read(3)
  + 'asd'
  + >>> f.seek(4)
  + >>> f.tell()
  + 4
  + >>> f.read(3)
  + 'qwe'
  + >>> f.tell()
  + 7
  + >>> f.close()
  """
  def __init__(self, name, mode='r'):
  