function Open-Solution() {
    $solutions = gci -recurse -path *.sln
    if ($solutions.Count -eq 1) {
        & $solutions.FullName
    } elseif ($solutions.Count -eq 0) {
        write-host "I couldn't find any solution files here!"
    } elseif ($solutions.Count -gt 1) {
        write-host "I found more than solution. Which one do you want to open?"
        $solutions | % { write-host " - $($_.FullName)" }
    }
}

New-Alias sln Open-Solution