gRPC does not support streaming interfaces?

Error when calling transaction with a Channel argument:
julia> channel = Channel{GraknClient.grakn.protocol.Transaction_Client}(1)

julia> txn = GraknClient.transaction(client.core_stub.blockingStub, gRPCController(), channel)
ERROR: MethodError: no method matching meta(::Type{Channel{GraknClient.grakn.protocol.Transaction_Client}})
Closest candidates are:
  meta(::ProtoBuf.ProtoMeta, ::Type, ::Vector{Pair{Symbol, Union{String, Type}}}, ::Vector{Symbol}, ::Vector{Int64}, ::Dict{Symbol, Any}) at /Users/tomkwong/.julia/packages/ProtoBuf/NJbMU/src/codec.jl:576
  meta(::ProtoBuf.ProtoMeta, ::Type, ::Vector{Pair{Symbol, Union{String, Type}}}, ::Vector{Symbol}, ::Vector{Int64}, ::Dict{Symbol, Any}, ::Vector{Symbol}) at /Users/tomkwong/.julia/packages/ProtoBuf/NJbMU/src/codec.jl:576
  meta(::ProtoBuf.ProtoMeta, ::Type, ::Vector{Pair{Symbol, Union{String, Type}}}, ::Vector{Symbol}, ::Vector{Int64}, ::Dict{Symbol, Any}, ::Vector{Symbol}, ::Dict) at /Users/tomkwong/.julia/packages/ProtoBuf/NJbMU/src/codec.jl:576
  ...
Stacktrace:
 [1] writeproto(io::IOBuffer, obj::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ ProtoBuf ~/.julia/packages/ProtoBuf/NJbMU/src/codec.jl:419
 [2] to_delimited_message_bytes(msg::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ gRPC ~/.julia/packages/gRPC/BiThx/src/common.jl:19
 [3] write_request(channel::gRPC.gRPCChannel, controller::gRPCController, service::ProtoBuf.ServiceDescriptor, method::ProtoBuf.MethodDescriptor, request::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ gRPC ~/.julia/packages/gRPC/BiThx/src/client.jl:16
 [4] call_method(channel::gRPC.gRPCChannel, service::ProtoBuf.ServiceDescriptor, method::ProtoBuf.MethodDescriptor, controller::gRPCController, request::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ gRPC ~/.julia/packages/gRPC/BiThx/src/server.jl:66
 [5] call_method(stub::ProtoBuf.ProtoServiceBlockingStub, meth::ProtoBuf.MethodDescriptor, controller::gRPCController, request::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ ProtoBuf ~/.julia/packages/ProtoBuf/NJbMU/src/svc.jl:100
 [6] transaction(stub::GraknCoreBlockingStub, controller::gRPCController, inp::Channel{GraknClient.grakn.protocol.Transaction_Client})
   @ GraknClient ~/OpenSource/GraknClient.jl/src/generated/core_service_pb.jl:56
 [7] top-level scope
   @ REPL[10]:1
 [8] eval
   @ ./boot.jl:360 [inlined]
tk3369/error.md
