我在如何更改数据类型时遇到此错误：

错误：

raise _Rendezvous(state,None,deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
status = StatusCode.INVALID_ARGUMENT
details = "Expects arg[0] to be float but string is provided"
debug_error_string = "{"created":"@1574400948.336107855","description":"Error received from peer ipv6:[::1]:8500","file":"src/core/lib/surface/call.cc","file_line":1055,"grpc_message":"Expects arg[0] to be float but string is provided","grpc_status":3}