> import json
  > with open("config.json") as f:
  >  contents = f.read()
  > config = json.loads(contents)

translates to:

  extern crate serde_json as json;

  fn read_json() -> Result<json::Value, Box<std::error::Error>> {
      let file = std::fs::File::open("config.json")?;
      let config = json::from_reader(&file)?;
      Ok(config)
  }

And

  > import configparser
  > config = ConfigParser()
  > config.read("config.conf")

can be translated to:

  extern crate config;
  use config::{Config, File, FileFormat};

  fn read_config() -> Result<Config, Box<std::error::Error>> {
      let mut c = Config::new();
      c.merge(File::new("config", FileFormat::Json))?;
      Ok(c)
  }

Difficult stuff indeed.