function FindInstalledGem {

param($gemName, $gemVersion)

$nameVer = $(Invoke-Expression "gem list --local" | Select-String "^$gemName").Line
if ($nameVer.StartsWith($gemName)) {
  if ($gemVersion) {
    $versions = ($nameVer -split { $_ -eq "(" -or $_ -eq ")"})[1].split(", ")
    if ($versions.Contains($gemVersion)) {
      $true
    } else {
      $false
    }
  } else {
    $true
  }
} else {
  $false
}

}