\name{getGOLevel}
\alias{getGOLevel}
\title{get GOIDs at a specific level}
\usage{getGOLevel(ont, level)}
\description{query GOIDs at a specific level.}
\value{a vector of GOIDs}
\author{Guangchuang Yu \url{http://ygc.name}}
\arguments{\item{ont}{Ontology}
\item{level}{GO level}}