KeepChar - script and chart function

KeepChar() returns a string consisting of the first string ,'text', less any of the characters NOT contained in the second string, "keep_chars".

Syntax:  

KeepChar(text, keep_chars)

Return data type: string

Arguments:  

T1:
Load 
*, 
keepchar(String1, String2) as KeepChar;  
Load * inline [
String1, String2
'a1b2c3', '123'
];