parameters: (self, source)
return_statement: return source in self.sources
docstring: For *in* test.
docstring_summary: For *in* test.
docstring_tokens: For * in * test .
function: def __contains__(self, source):
          """For *in* test.
          """
          return source in self.sources
function_tokens: def __contains__ ( self , source ) : return source in self . sources