Channel reuse on unary endpoint

Can `grpcurl` re-use the gRPC channel to perform multiple queries on a unary endpoint?

I'm doing something like

```shell
grpcurl -plaintext -d '{"height": 1}' localhost:9090 path.to.SomeEndpoint
grpcurl -plaintext -d '{"height": 2}' localhost:9090 path.to.SomeEndpoint
...
grpcurl -plaintext -d '{"height": N}' localhost:9090 path.to.SomeEndpoint
```

and I wonder if there's a better approach.

My endpoint doesn't support streaming, i.e.,

```shell
grpcurl -plaintext -d '{"height": 1}{"height": 2}' localhost:9090 path.to.SomeEndpoint
```

is not supported.

Thank you for this wonder tool!

The issue names only the grpcurl command and a unary endpoint; no files, tests, or implementation entry points are provided. Start by locating the command handling for repeated invocations and determine the intended channel-reuse behavior and completion criteria before estimating the work.

Written by the indexing model from the issue text.