$foo = "this is the original text"  
 
function f1($str)  
{  
"Calling f1..."  
$str.toUpper()  
}  
 
function f2($value)  
{ . 
"Calling f2... what is value?" . 
$value | get-member . 

"" 
"Before f1 value is: " + $value 
"Before f1 foo is: " + $script:foo 
$script:foo = f1 $value
"after f1 value is: " + $value
"after f1 foo is: " + $script:foo
}

""
"BEFORE PASS 1, WHAT IS FOO?"
$foo | get-member
"" 
 
"PASS 1"
f2 $foo

"" 
"AFTER PASS 1, WHAT IS FOO?"
$foo | get-member
"" 
 
""
"PASS 2"
f2 $foo

""
"global value"
$foo