def hasHostKey(self, hostname, key):
        """
        Check for an entry with matching hostname and key.

        @param hostname: A hostname or IP address literal to check for.
        @type hostname: L{bytes}

        @param key: The public key to check for.
        @type key: L{Key}

        @return: C{True} if the given hostname and key are present in this file,
            C{False} if they are not.
        @rtype: L{bool}

        @raise HostKeyChanged: if the host key found for the given hostname
            does not match the given key.
        """
        for lineidx, entry in enumerate(self.iterentries(), -len(self._added)):
            if entry.matchesHost(hostname) and entry.keyType == key.sshType():
                if entry.matchesKey(key):
                    return True
                else:
                    # Notice that lineidx is 0-based but HostKeyChanged.lineno
                    # is 1-based.
                    if lineidx < 0:
                        line = None
                        path = None
                    else:
                        line = lineidx + 1
                        path = self._savePath
                    raise HostKeyChanged(entry, path, line)
        return False

        Check for an entry with matching hostname and key.

        @param hostname: A hostname or IP address literal to check for.
        @type hostname: L{bytes}

        @param key: The public key to check for.
        @type key: L{Key}

        @return: C{True} if the given hostname and key are present in this file,
            C{False} if they are not.
        @rtype: L{bool}

        @raise HostKeyChanged: if the host key found for the given hostname
            does not match the given key.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/client/knownhosts.py