Merge branch 'master' into network-options

diff --cc httpx/__init__.py
Simple merge

diff --cc httpx/_config.py
index 1af8a4565aaec4f6e7d2145d6f6d12ced4734d91,6662ea806733833e81c94a3c3b86f59ddb4f209d..736cfdf38d19ed76f03cc5e5957fde314d6a7fd6
--- 1/httpx/_config.py
--- 2/httpx/_config.py
+++ b/httpx/_config.py
@@@ -12,12 -14,8 +14,14 @@@ from ._types import CertTypes, HeaderTy
  from ._urls import URL
  from ._utils import get_ca_bundle_from_env
  
+ __all__ = ["Limits", "Proxy", "Timeout", "create_ssl_context"]
+ 
 +SOCKET_OPTION = typing.Union[
 +    typing.Tuple[int, int, int],
 +    typing.Tuple[int, int, typing.Union[bytes, bytearray]],
 +    typing.Tuple[int, int, None, int],
 +]
 +
  DEFAULT_CIPHERS = ":".join(
      [
          "ECDHE+AESGCM",

diff --cc httpx/_transports/default.py
index 0829b5704cee2fef5ee911c09b80dbfa9bceea29,33db416dd19f4247c4814a18e79378eafd2337e0..1896059ec403d24e5e83ee99319538f501595a9a
--- 1/httpx/_transports/default.py
--- 2/httpx/_transports/default.py
+++ b/httpx/_transports/default.py
@@@ -61,7 -57,15 +64,17 @@@ from .base import AsyncBaseTransport, B
  T = typing.TypeVar("T", bound="HTTPTransport")
  A = typing.TypeVar("A", bound="AsyncHTTPTransport")
  
 -__all__ = ["AsyncHTTPTransport", "HTTPTransport"]
 -
 +
++__all__ = ["AsyncHTTPTransport", "HTTPTransport"]
++
++
+ SOCKET_OPTION = typing.Union[
+     typing.Tuple[int, int, int],
+     typing.Tuple[int, int, typing.Union[bytes, bytearray]],
+     typing.Tuple[int, int, None, int],
+ ]
+ 
+ 
  @contextlib.contextmanager
  def map_httpcore_exceptions() -> typing.Iterator[None]:
      try: