def normalise_key( key, calling_method_name )
      unless key.is_a?( String ) || key.is_a?( Symbol )
        raise "Hoodoo::TransientStore\##{ calling_method_name }: Keys must be of String or Symbol class; you provided '#{ key.class }'"
      end

      key = key.to_s

      if key.empty?
        raise "Hoodoo::TransientStore\##{ calling_method_name }: Empty String or Symbol keys are prohibited"
      end

      return key
    end
def normalise_key( key, calling_method_name )
      unless key.is_a?( String ) || key.is_a?( Symbol )
        raise "Hoodoo::TransientStore\##{ calling_method_name }: Keys must be of String or Symbol class; you provided '#{ key.class }'"
      end

      key = key.to_s

      if key.empty?
        raise "Hoodoo::TransientStore\##{ calling_method_name }: Empty String or Symbol keys are prohibited"
      end

      return key
    end
Given a storage key, make sure it's a String or Symbol, coerce to a
 String and ensure it isn't empty. Returns the non-empty String version.
 Raises exceptions for bad input classes or empty keys.

 +key+::                 Key to normalise.

 +calling_method_name+:: Name of calling method to declare in exception
                         messages, to aid callers in debugging.