code: function(arg_hash){
  
  	if( ! arg_hash ){ arg_hash = {}; }
  	var out_keys = [];
  	for (var out_key in arg_hash) {
  	    if (arg_hash.hasOwnProperty(out_key)) {
  		out_keys.push(out_key);
  	    }
  	}
  	
  	return out_keys;
      }
docs: Get the hash keys from a hash/object, return as an array.
  
  @param {} arg_hash - the hash in question
  @returns {Array} an array of keys