function rvm_require_ruby 
{
  if ! rvm list strings | grep -q "^$1" ; then
    echo "ERROR: Requires Ruby Version: '$1'"
    return 1
  fi
  return 0
}

function rvm_use 
{
  rvm_require_ruby $1
  if [[ $? -gt 0 ]] ; then
    # handle the error
    exit
  fi
  rvm use $1

  return $?
}

function rvm_require_gemset 
{
  if ! rvm gemset list | grep -q "^$1" ; then
    echo "ERROR: Requires RVM Gemset: '$1'"
    return 1
  fi
  return 0
}

function rvm_gemset_use 
{
  rvm_require_gemset "$1"
  if [[ $? -gt 0 ]] ; then
    # handle the error
    exit
  fi
  rvm gemset use "$1"
}