API SDK GraphQL
For all the GraphQL operations, there is a folder named graphql_operation which contains all the queries. graphql_handler.dart is used to handle this and it contains all the functions to query or mutate a client. 
In api_constants.dart, set the GraphQLClient with _httpLink and _authLink. Next, in the main.dart file for API SDK, call a function to get the data. For example, there is a function for accessing Github repositories:
The client() comes from api_constants.dart.
Use the following to call the function: