Map iterator not initialised despite using keyword typename

I wrote a function that checks if a certain index is present in a map.

#include <netdb.h> 
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <map>
#include <string>
#include <vector>
#include <iterator>


bool search(typename std::map<std::string, std::string> m, std::string s) {
typename std::map<std::string, std::string>::iterator mi;
mi= m.find(s);
if(mi != m.end())
    return true;
else
    return false;
}

When I tried to compile the code using the g++ compiler on Ubuntu, the error message I got for the line :

‘mi’ was not declared in this scope.

Earlier I had not included the keyword typename, I changed that on reading the answer to a similar question here however I still had the same problem. The code involves socket programming and the map is used for a key value store implemented at the server end, hence the relevant header files.