Retrieve an item from a Python object, similar to how
x[name] might be used in Python code to access an
item indexed by key on an object x. The object's
__getitem__ method will be called.
py_get_item(x, key, silent = FALSE)A Python object.
The key used for item lookup.
Boolean; when TRUE, attempts to access
missing items will return NULL rather than
throw an error.
Other item-related APIs: py_del_item,
py_set_item