def retrieve(self, id) :
_, _, source = self.http_client.get("<STR_LIT>".format(id=id))<EOL>return source<EOL>
Retrieve a single source

Returns a single source available to the user by the provided id
If a source with the supplied unique identifier does not exist it returns an error

:calls: ``get /sources/{id}``
:param int id: Unique identifier of a Source.
:return: Dictionary that support attriubte-style access and represent Source resource.
:rtype: dict