Pass function as argument in PowerShell

passfunc.ps1

function Reverse-String {
  param(
    [string]$instr
  )

  $chars = $instr.ToCharArray()

  [array]::Reverse($chars)
  $chars -join ""
}

Invoke-Command {
  param($string,$func)
  [scriptblock]::Create($func).Invoke($string)
} -ArgumentList "abc",${function:Reverse-String}