1 files changed, 47 insertions, 0 deletions
diff --git a/coverage/types.py b/coverage/types.py
new file mode 100644
index 00000000..23c7ef8b
--- /dev/null
+++ b/coverage/types.py
@@ -0,0 +1,47 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+"""
+Types for use throughout coverage.py.
+"""
+
+from typing import Dict, List, Optional, Tuple, Union, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    # Protocol is new in 3.8.  PYVERSIONS
+    from typing import Protocol
+else:
+    class Protocol:             # pylint: disable=missing-class-docstring
+        pass
+
+# One value read from a config file.
+TConfigValue = Union[str, List[str]]
+# An entire config section, mapping option names to values.
+TConfigSection = Dict[str, TConfigValue]
+
+class TConfigurable(Protocol):
+    """Something that can proxy to the coverage configuration settings."""
+
+    def get_option(self, option_name: str) -> Optional[TConfigValue]:
+        """Get an option from the configuration.
+
+        `option_name` is a colon-separated string indicating the section and
+        option name.  For example, the ``branch`` option in the ``[run]``
+        section of the config file would be indicated with `"run:branch"`.
+
+        Returns the value of the option.
+
+        """
+
+    def set_option(self, option_name: str, value: Union[TConfigValue, TConfigSection]) -> None:
+        """Set an option in the configuration.
+
+        `option_name` is a colon-separated string indicating the section and
+        option name.  For example, the ``branch`` option in the ``[run]``
+        section of the config file would be indicated with `"run:branch"`.
+
+        `value` is the new value for the option.
+
+        """
+
+TArc = Tuple[int, int]