Groovy script to execute powershell commands on Jenkins

powershell.groovy

def exec(Map map = [:], command){
		
	def debug =  map.debug ?: false

	if (debug) echo "[DEBUG] powershell method called with parameter: \n $command"

	def returnFileName = new Date().format("yyyyMMddHHmmssSSS")
	if (debug) echo "[DEBUG] The return file name will is $returnFileName"
	
	def pwCommand =  "powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile  -Command \"$command\" > $returnFileName"
	if(debug) echo "[DEBUG] The following command will be executed: \n $pwCommand"
	bat pwCommand
	
	if(debug) echo "[DEBUG] Reading the file $returnFileName"
	def pwret = readFile "$returnFileName"
	pwret = pwret.trim()
	
	if(debug) echo "[DEBUG] Deleting the file $returnFileName"
	bat "del $returnFileName"
	
	return pwret
}

return this

To run this script you can load the external file and call the exec method.

def powershell = load 'powershell.groovy'
powershell.exec('ls')

How do you do this? Is the Groovy file supposed to be stored somewhere on Jenkins machine?