code: function krillPrimValidateLog(pred, key)
  {
  	var ii;
  
  	if (!pred[key])
  		throw (new VError('predicate %j: expected "%s" in logical ' +
  		    'expression', pred, key));
  
  	if (!(pred[key] instanceof Array))
  		throw (new VError('predicate %j: operator "%s": expected array',
  		    pred, key));
  
  	if (pred[key].length < 2)
  		throw (new VError('predicate %j: operator "%s": expected at ' +
  		    'least 2 elements in array', pred, key));
  
  	for (ii = 0; ii < pred[key].length; ii++)
  		krillPrimValidateSyntax(pred[key][ii]);
  }
docs: /*
  Validates that the logical expression has a valid format. This means that it
  is of the format:
  { key: [ obj, obj,... ] }
  
  Input:
  - pred: The current predicate
  - key: The key that we're interested in
  
  On Return the following points have been validated:
  - The key points to an array of at least length two
  - Every object in the array is a valid predicate or logical expression