allow user-created instances of PySequence and PyIterable

allow user-created instances of PySequence and PyIterable · pythonnet/pythonnet@c09de96

Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,18 @@ internal PyIterable(IntPtr ptr) : base(ptr)`
`13`	`13`	`internal PyIterable(BorrowedReference reference) : base(reference) { }`
`14`	`14`	`internal PyIterable(in StolenReference reference) : base(reference) { }`
`15`	`15`
	`16`	`+/// <summary>`
	`17`	`+/// Creates new instance from an existing object.`
	`18`	`+/// </summary>`
	`19`	`+/// <remarks>This constructor does not check if <paramref name="o"/> is actually iterable.</remarks>`
	`20`	`+public PyIterable(PyObject o) : base(FromObject(o)) { }`
	`21`	`+`
	`22`	`+static BorrowedReference FromObject(PyObject o)`
	`23`	`+{`
	`24`	`+if (o is null) throw new ArgumentNullException(nameof(o));`
	`25`	`+return o.Reference;`
	`26`	`+}`
	`27`	`+`
`16`	`28`	`/// <summary>`
`17`	`29`	`/// Return a new PyIter object for the object. This allows any iterable`
`18`	`30`	`/// python object to be iterated over in C#. A PythonException will be`