Get the file size of the remote file.

def remote_file_size(self, remote_cmd="", remote_file=None):
        """Get the file size of the remote file."""
        if remote_file is None:
            if self.direction == "put":
                remote_file = self.dest_file
            elif self.direction == "get":
                remote_file = self.source_file
        if not remote_cmd:
            remote_cmd = "dir {}/{}".format(self.file_system, remote_file)
        remote_out = self.ssh_ctl_chan.send_command(remote_cmd)
        # Strip out "Directory of flash:/filename line
        remote_out = re.split(r"Directory of .*", remote_out)
        remote_out = "".join(remote_out)
        # Match line containing file name
        escape_file_name = re.escape(remote_file)
        pattern = r".*({}).*".format(escape_file_name)
        match = re.search(pattern, remote_out)
        if match:
            line = match.group(0)
            # Format will be 26  -rw-   6738  Jul 30 2016 19:49:50 -07:00  filename
            file_size = line.split()[2]
        if "Error opening" in remote_out or "No such file or directory" in remote_out:
            raise IOError("Unable to find file on remote system")
        else:
            return int(file_size)