--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/pluggy/callers.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,208 @@
+"""
+Call loop machinery
+"""
+import sys
+import warnings
+
+_py3 = sys.version_info > (3, 0)
+
+
+if not _py3:
+    exec(
+        """
+def _reraise(cls, val, tb):
+    raise cls, val, tb
+"""
+    )
+
+
+def _raise_wrapfail(wrap_controller, msg):
+    co = wrap_controller.gi_code
+    raise RuntimeError(
+        "wrap_controller at %r %s:%d %s"
+        % (co.co_name, co.co_filename, co.co_firstlineno, msg)
+    )
+
+
+class HookCallError(Exception):
+    """ Hook was called wrongly. """
+
+
+class _Result(object):
+    def __init__(self, result, excinfo):
+        self._result = result
+        self._excinfo = excinfo
+
+    @property
+    def excinfo(self):
+        return self._excinfo
+
+    @property
+    def result(self):
+        """Get the result(s) for this hook call (DEPRECATED in favor of ``get_result()``)."""
+        msg = "Use get_result() which forces correct exception handling"
+        warnings.warn(DeprecationWarning(msg), stacklevel=2)
+        return self._result
+
+    @classmethod
+    def from_call(cls, func):
+        __tracebackhide__ = True
+        result = excinfo = None
+        try:
+            result = func()
+        except BaseException:
+            excinfo = sys.exc_info()
+
+        return cls(result, excinfo)
+
+    def force_result(self, result):
+        """Force the result(s) to ``result``.
+
+        If the hook was marked as a ``firstresult`` a single value should
+        be set otherwise set a (modified) list of results. Any exceptions
+        found during invocation will be deleted.
+        """
+        self._result = result
+        self._excinfo = None
+
+    def get_result(self):
+        """Get the result(s) for this hook call.
+
+        If the hook was marked as a ``firstresult`` only a single value
+        will be returned otherwise a list of results.
+        """
+        __tracebackhide__ = True
+        if self._excinfo is None:
+            return self._result
+        else:
+            ex = self._excinfo
+            if _py3:
+                raise ex[1].with_traceback(ex[2])
+            _reraise(*ex)  # noqa
+
+
+def _wrapped_call(wrap_controller, func):
+    """ Wrap calling to a function with a generator which needs to yield
+    exactly once.  The yield point will trigger calling the wrapped function
+    and return its ``_Result`` to the yield point.  The generator then needs
+    to finish (raise StopIteration) in order for the wrapped call to complete.
+    """
+    try:
+        next(wrap_controller)  # first yield
+    except StopIteration:
+        _raise_wrapfail(wrap_controller, "did not yield")
+    call_outcome = _Result.from_call(func)
+    try:
+        wrap_controller.send(call_outcome)
+        _raise_wrapfail(wrap_controller, "has second yield")
+    except StopIteration:
+        pass
+    return call_outcome.get_result()
+
+
+class _LegacyMultiCall(object):
+    """ execute a call into multiple python functions/methods. """
+
+    # XXX note that the __multicall__ argument is supported only
+    # for pytest compatibility reasons.  It was never officially
+    # supported there and is explicitely deprecated since 2.8
+    # so we can remove it soon, allowing to avoid the below recursion
+    # in execute() and simplify/speed up the execute loop.
+
+    def __init__(self, hook_impls, kwargs, firstresult=False):
+        self.hook_impls = hook_impls
+        self.caller_kwargs = kwargs  # come from _HookCaller.__call__()
+        self.caller_kwargs["__multicall__"] = self
+        self.firstresult = firstresult
+
+    def execute(self):
+        caller_kwargs = self.caller_kwargs
+        self.results = results = []
+        firstresult = self.firstresult
+
+        while self.hook_impls:
+            hook_impl = self.hook_impls.pop()
+            try:
+                args = [caller_kwargs[argname] for argname in hook_impl.argnames]
+            except KeyError:
+                for argname in hook_impl.argnames:
+                    if argname not in caller_kwargs:
+                        raise HookCallError(
+                            "hook call must provide argument %r" % (argname,)
+                        )
+            if hook_impl.hookwrapper:
+                return _wrapped_call(hook_impl.function(*args), self.execute)
+            res = hook_impl.function(*args)
+            if res is not None:
+                if firstresult:
+                    return res
+                results.append(res)
+
+        if not firstresult:
+            return results
+
+    def __repr__(self):
+        status = "%d meths" % (len(self.hook_impls),)
+        if hasattr(self, "results"):
+            status = ("%d results, " % len(self.results)) + status
+        return "<_MultiCall %s, kwargs=%r>" % (status, self.caller_kwargs)
+
+
+def _legacymulticall(hook_impls, caller_kwargs, firstresult=False):
+    return _LegacyMultiCall(
+        hook_impls, caller_kwargs, firstresult=firstresult
+    ).execute()
+
+
+def _multicall(hook_impls, caller_kwargs, firstresult=False):
+    """Execute a call into multiple python functions/methods and return the
+    result(s).
+
+    ``caller_kwargs`` comes from _HookCaller.__call__().
+    """
+    __tracebackhide__ = True
+    results = []
+    excinfo = None
+    try:  # run impl and wrapper setup functions in a loop
+        teardowns = []
+        try:
+            for hook_impl in reversed(hook_impls):
+                try:
+                    args = [caller_kwargs[argname] for argname in hook_impl.argnames]
+                except KeyError:
+                    for argname in hook_impl.argnames:
+                        if argname not in caller_kwargs:
+                            raise HookCallError(
+                                "hook call must provide argument %r" % (argname,)
+                            )
+
+                if hook_impl.hookwrapper:
+                    try:
+                        gen = hook_impl.function(*args)
+                        next(gen)  # first yield
+                        teardowns.append(gen)
+                    except StopIteration:
+                        _raise_wrapfail(gen, "did not yield")
+                else:
+                    res = hook_impl.function(*args)
+                    if res is not None:
+                        results.append(res)
+                        if firstresult:  # halt further impl calls
+                            break
+        except BaseException:
+            excinfo = sys.exc_info()
+    finally:
+        if firstresult:  # first result hooks return a single value
+            outcome = _Result(results[0] if results else None, excinfo)
+        else:
+            outcome = _Result(results, excinfo)
+
+        # run all wrapper post-yield blocks
+        for gen in reversed(teardowns):
+            try:
+                gen.send(outcome)
+                _raise_wrapfail(gen, "has second yield")
+            except StopIteration:
+                pass
+
+        return outcome.get_result()