Ignore object properties examples

See PyO3#387

Author: Alexander-N

guide/src/class.md

@@ -230,7 +230,7 @@ If function name starts with `get_` or `set_` for getter or setter respectively.
 Descriptor name becomes function name with prefix removed. This is useful in case of
 rust's special keywords like `type`.
 
-```rust
+```rust,ignore
 # extern crate pyo3;
 # use pyo3::prelude::*;
 # #[pyclass]
@@ -259,7 +259,7 @@ In this case property `num` is defined. And it is available from python code as
 Also both `#[getter]` and `#[setter]` attributes accepts one parameter.
 If this parameter is specified, it is used as a property name. i.e.
 
-```rust
+```rust,ignore
 # extern crate pyo3;
 # use pyo3::prelude::*;
 # #[pyclass]
@@ -287,7 +287,7 @@ In this case the property `number` is defined and is available from python code
 
 For simple cases you can also define getters and setters in your Rust struct field definition, for example:
 
-```rust
+```rust,ignore
 # extern crate pyo3;
 # use pyo3::prelude::*;
 #[pyclass]