\name{print_help}
\alias{print_help}
\title{Printing an usage message from an OptionParser object}
\usage{
  print_help(object)
}
\arguments{
  \item{object}{A \code{OptionParser} instance.}
}
\value{
  \code{print_help} uses the \code{cat} function to print
  out a usage message.  It returns \code{invisible(NULL)}.
}
\description{
  \code{print_help} print an usage message from an
  OptionParser object, usually called by \code{parse_args}
  when it encounters a help option.
}
\author{
  Trevor Davis.
}
\references{
  Python's \code{optparse} library, which inspired this
  package, is described here:
  \url{http://docs.python.org/library/optparse.html}
}
\seealso{
  \code{{parse_args}} \code{{OptionParser}}
}

