Replace instances of a substring within a string with another string.
Searches for all instances of the find-string in provided variable and replaces them with replace-string. If replace-string is an empty string, this will effecively delete that substring. If max-replacements is specified, this function will stop after performing replacements max-replacements times.
The replacement only occurs in the output. The original variable is not altered.
This documentation was imported from Asterisk Version Unknown