Interceptor on client side. See GRPC.Stub.connect/2.
GRPC.Stub.connect/2
@callback call( stream :: GRPC.Client.Stream.t(), req :: struct() | nil, next :: (GRPC.Client.Stream.t(), req :: struct() | nil -> GRPC.Stub.rpc_return()), options :: any() ) :: GRPC.Stub.rpc_return()
@callback init(options :: any()) :: options :: any()