How to use the pynvim.compat.IS_PYTHON3 function in pynvim

"""Event loop abstraction subpackage.

Tries to use pyuv as a backend, falling back to the asyncio implementation.
"""

from ...compat import IS_PYTHON3

# on python3 we only support asyncio, as we expose it to plugins
if IS_PYTHON3:
    from .asyncio import AsyncioEventLoop
    EventLoop = AsyncioEventLoop
else:
    try:
        # libuv is fully implemented in C, use it when available
        from .uv import UvEventLoop
        EventLoop = UvEventLoop
    except ImportError:
        # asyncio(trollius on python 2) is pure python and should be more
        # portable across python implementations
        from .asyncio import AsyncioEventLoop
        EventLoop = AsyncioEventLoop


__all__ = ('EventLoop')

"""Set handlers for plugin_load/plugin_unload."""
        self.nvim = nvim
        self._specs = {}
        self._loaded = {}
        self._load_errors = {}
        self._notification_handlers = {
            'nvim_error_event': self._on_error_event
        }
        self._request_handlers = {
            'poll': lambda: 'ok',
            'specs': self._on_specs_request,
            'shutdown': self.shutdown
        }

        # Decode per default for Python3
        self._decode_default = IS_PYTHON3

def from_session(cls, session):
        """Create a new Nvim instance for a Session instance.

        This method must be called to create the first Nvim instance, since it
        queries Nvim metadata for type information and sets a SessionHook for
        creating specialized objects from Nvim remote handles.
        """
        session.error_wrapper = lambda e: NvimError(decode_if_bytes(e[1]))
        channel_id, metadata = session.request(b'nvim_get_api_info')

        if IS_PYTHON3:
            # decode all metadata strings for python3
            metadata = walk(decode_if_bytes, metadata)

        types = {
            metadata['types']['Buffer']['id']: Buffer,
            metadata['types']['Window']['id']: Window,
            metadata['types']['Tabpage']['id']: Tabpage,
        }

        return cls(session, channel_id, metadata, types)

def plugin(cls):
    """Tag a class as a plugin.

    This decorator is required to make the class methods discoverable by the
    plugin_load method of the host.
    """
    cls._nvim_plugin = True
    # the _nvim_bind attribute is set to True by default, meaning that
    # decorated functions have a bound Nvim instance as first argument.
    # For methods in a plugin-decorated class this is not required, because
    # the class initializer will already receive the nvim object.
    predicate = lambda fn: hasattr(fn, '_nvim_bind')
    for _, fn in inspect.getmembers(cls, predicate):
        if IS_PYTHON3:
            fn._nvim_bind = False
        else:
            fn.im_func._nvim_bind = False
    return cls

This will automatically close the session when you're done with it, or
    when an error occured.


    """
    session = (tcp_session(address, port) if session_type == 'tcp' else
               socket_session(path) if session_type == 'socket' else
               stdio_session() if session_type == 'stdio' else
               child_session(argv) if session_type == 'child' else
               None)

    if not session:
        raise Exception('Unknown session type "%s"' % session_type)

    if decode is None:
        decode = IS_PYTHON3

    return Nvim.from_session(session).with_decode(decode)

def _on_request(self, name, args):
        """Handle a msgpack-rpc request."""
        if IS_PYTHON3:
            name = decode_if_bytes(name)
        handler = self._request_handlers.get(name, None)
        if not handler:
            msg = self._missing_handler_error(name, 'request')
            error(msg)
            raise ErrorResponse(msg)

        debug('calling request handler for "%s", args: "%s"', name, args)
        rv = handler(*args)
        debug("request handler for '%s %s' returns: %s", name, args, rv)
        return rv

"""API for working with a Nvim Buffer."""
from .common import Remote
from ..compat import IS_PYTHON3, check_async


__all__ = ('Buffer')


if IS_PYTHON3:
    basestring = str


def adjust_index(idx, default=None):
    """Convert from python indexing convention to nvim indexing convention."""
    if idx is None:
        return default
    elif idx < 0:
        return idx - 1
    else:
        return idx


class Buffer(Remote):

    """A remote Nvim buffer."""