code: func (ns *Namespace) ReadFile(i interface{}) (string, error) {
  	s, err := cast.ToStringE(i)
  	if err != nil {
  		return "", err
  	}
  
  	return readFile(ns.readFileFs, s)
  }
docs: // ReadFile reads the file named by filename relative to the configured WorkingDir.
  // It returns the contents as a string.
  // There is an upper size limit set at 1 megabytes.