def sysfind(cls, name, checker=None, paths=None):
        """Return a path object found by looking at the systems
        underlying PATH specification. If the checker is not None
        it will be invoked to filter matching paths.  If a binary
        cannot be found, None is returned
        Note: This is probably not working on plain win32 systems
        but may work on cygwin.
        """
        if isabs(name):
            p = local(name)
            if p.check(file=1):
                return p
        else:
            if paths is None:
                if iswin32:
                    paths = os.environ["Path"].split(";")
                    if "" not in paths and "." not in paths:
                        paths.append(".")
                    try:
                        systemroot = os.environ["SYSTEMROOT"]
                    except KeyError:
                        pass
                    else:
                        paths = [
                            path.replace("%SystemRoot%", systemroot) for path in paths
                        ]
                else:
                    paths = os.environ["PATH"].split(":")
            tryadd = []
            if iswin32:
                tryadd += os.environ["PATHEXT"].split(os.pathsep)
            tryadd.append("")

            for x in paths:
                for addext in tryadd:
                    p = local(x).join(name, abs=True) + addext
                    try:
                        if p.check(file=1):
                            if checker:
                                if not checker(p):
                                    continue
                            return p
                    except error.EACCES:
                        pass
        return None
Return a path object found by looking at the systems
        underlying PATH specification. If the checker is not None
        it will be invoked to filter matching paths.  If a binary
        cannot be found, None is returned
        Note: This is probably not working on plain win32 systems
        but may work on cygwin.
        
src/_pytest/_py/path.py